Diff: dxml.cpp

Revision:

2:45b351b4fc2a

Child:

4:7abcf4543282

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dxml.cpp	Sun Apr 05 12:56:41 2020 +0000
@@ -0,0 +1,991 @@
+#define dxml_NOMMAP
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+#include <ctype.h>
+//#include <unistd.h>
+//#include <sys/types.h>
+#ifndef dxml_NOMMAP
+#include <sys/mman.h>
+#endif // dxml_NOMMAP
+//#include <stat.h>
+#include "dxml.h"
+
+#define dxml_WS   "\t\r\n "  // whitespace
+#define dxml_ERRL 128        // maximum error string length
+
+char* strdup(const char* literal)
+{
+    auto l_len = strlen(literal);
+    auto n = new char[l_len + 1];
+    strncpy(n, literal, l_len + 1);
+    return n;
+}
+
+typedef struct dxml_root *dxml_root_t;
+struct dxml_root {       // additional data for the root tag
+    struct dxml xml;     // is a super-struct built on top of dxml struct
+    dxml_t cur;          // current xml tree insertion point
+    char *m;              // original xml string
+    size_t len;           // length of allocated memory for mmap, -1 for malloc
+    char *u;              // UTF-8 conversion of string if original was UTF-16
+    char *s;              // start of work area
+    char *e;              // end of work area
+    char **ent;           // general entities (ampersand sequences)
+    char ***attr;         // default attributes
+    char ***pi;           // processing instructions
+    short standalone;     // non-zero if <?xml standalone="yes"?>
+    char err[dxml_ERRL]; // error string
+};
+
+char *dxml_NIL[] = { NULL }; // empty, null terminated array of strings
+
+// returns the first child tag with the given name or NULL if not found
+dxml_t dxml_child(dxml_t xml, const char *name)
+{
+    xml = (xml) ? xml->child : NULL;
+    while (xml && strcmp(name, xml->name)) xml = xml->sibling;
+    return xml;
+}
+
+// returns the Nth tag with the same name in the same subsection or NULL if not
+// found
+dxml_t dxml_idx(dxml_t xml, int idx)
+{
+    for (; xml && idx; idx--) xml = xml->next;
+    return xml;
+}
+
+// returns the value of the requested tag attribute or NULL if not found
+const char *dxml_attr(dxml_t xml, const char *attr)
+{
+    int i = 0, j = 1;
+    dxml_root_t root = (dxml_root_t)xml;
+
+    if (! xml || ! xml->attr) return NULL;
+    while (xml->attr[i] && strcmp(attr, xml->attr[i])) i += 2;
+    if (xml->attr[i]) return xml->attr[i + 1]; // found attribute
+
+    while (root->xml.parent) root = (dxml_root_t)root->xml.parent; // root tag
+    for (i = 0; root->attr[i] && strcmp(xml->name, root->attr[i][0]); i++);
+    if (! root->attr[i]) return NULL; // no matching default attributes
+    while (root->attr[i][j] && strcmp(attr, root->attr[i][j])) j += 3;
+    return (root->attr[i][j]) ? root->attr[i][j + 1] : NULL; // found default
+}
+
+// same as dxml_get but takes an already initialized va_list
+dxml_t dxml_vget(dxml_t xml, va_list ap)
+{
+    char *name = va_arg(ap, char *);
+    int idx = -1;
+
+    if (name && *name) {
+        idx = va_arg(ap, int);    
+        xml = dxml_child(xml, name);
+    }
+    return (idx < 0) ? xml : dxml_vget(dxml_idx(xml, idx), ap);
+}
+
+// Traverses the xml tree to retrieve a specific subtag. Takes a variable
+// length list of tag names and indexes. The argument list must be terminated
+// by either an index of -1 or an empty string tag name. Example: 
+// title = dxml_get(library, "shelf", 0, "book", 2, "title", -1);
+// This retrieves the title of the 3rd book on the 1st shelf of library.
+// Returns NULL if not found.
+dxml_t dxml_get(dxml_t xml, ...)
+{
+    va_list ap;
+    dxml_t r;
+
+    va_start(ap, xml);
+    r = dxml_vget(xml, ap);
+    va_end(ap);
+    return r;
+}
+
+// returns a null terminated array of processing instructions for the given
+// target
+const char **dxml_pi(dxml_t xml, const char *target)
+{
+    dxml_root_t root = (dxml_root_t)xml;
+    int i = 0;
+
+    if (! root) return (const char **)dxml_NIL;
+    while (root->xml.parent) root = (dxml_root_t)root->xml.parent; // root tag
+    while (root->pi[i] && strcmp(target, root->pi[i][0])) i++; // find target
+    return (const char **)((root->pi[i]) ? root->pi[i] + 1 : dxml_NIL);
+}
+
+// set an error string and return root
+dxml_t dxml_err(dxml_root_t root, char *s, const char *err, ...)
+{
+    va_list ap;
+    int line = 1;
+    char *t, fmt[dxml_ERRL];
+    
+    for (t = root->s; t < s; t++) if (*t == '\n') line++;
+    snprintf(fmt, dxml_ERRL, "[error near line %d]: %s", line, err);
+
+    va_start(ap, err);
+    vsnprintf(root->err, dxml_ERRL, fmt, ap);
+    va_end(ap);
+
+    return &root->xml;
+}
+
+// Recursively decodes entity and character references and normalizes new lines
+// ent is a null terminated array of alternating entity names and values. set t
+// to '&' for general entity decoding, '%' for parameter entity decoding, 'c'
+// for cdata sections, ' ' for attribute normalization, or '*' for non-cdata
+// attribute normalization. Returns s, or if the decoded string is longer than
+// s, returns a malloced string that must be freed.
+char *dxml_decode(char *s, char **ent, char t)
+{
+    char *e, *r = s, *m = s;
+    long b, c, d, l;
+
+    for (; *s; s++) { // normalize line endings
+        while (*s == '\r') {
+            *(s++) = '\n';
+            if (*s == '\n') memmove(s, (s + 1), strlen(s));
+        }
+    }
+    
+    for (s = r; ; ) {
+        while (*s && *s != '&' && (*s != '%' || t != '%') && !isspace(*s)) s++;
+
+        if (! *s) break;
+        else if (t != 'c' && ! strncmp(s, "&#", 2)) { // character reference
+            if (s[2] == 'x') c = strtol(s + 3, &e, 16); // base 16
+            else c = strtol(s + 2, &e, 10); // base 10
+            if (! c || *e != ';') { s++; continue; } // not a character ref
+
+            if (c < 0x80) *(s++) = c; // US-ASCII subset
+            else { // multi-byte UTF-8 sequence
+                for (b = 0, d = c; d; d /= 2) b++; // number of bits in c
+                b = (b - 2) / 5; // number of bytes in payload
+                *(s++) = (0xFF << (7 - b)) | (c >> (6 * b)); // head
+                while (b) *(s++) = 0x80 | ((c >> (6 * --b)) & 0x3F); // payload
+            }
+
+            memmove(s, strchr(s, ';') + 1, strlen(strchr(s, ';')));
+        }
+        else if ((*s == '&' && (t == '&' || t == ' ' || t == '*')) ||
+                 (*s == '%' && t == '%')) { // entity reference
+            for (b = 0; ent[b] && strncmp(s + 1, ent[b], strlen(ent[b]));
+                 b += 2); // find entity in entity list
+
+            if (ent[b++]) { // found a match
+                if ((c = strlen(ent[b])) - 1 > (e = strchr(s, ';')) - s) {
+                    l = (d = (s - r)) + c + strlen(e); // new length
+                    r = (char*)((r == m) ? strcpy((char*)malloc(l), r) : realloc(r, l));
+                    e = strchr((s = r + d), ';'); // fix up pointers
+                }
+
+                memmove(s + c, e + 1, strlen(e)); // shift rest of string
+                strncpy(s, ent[b], c); // copy in replacement text
+            }
+            else s++; // not a known entity
+        }
+        else if ((t == ' ' || t == '*') && isspace(*s)) *(s++) = ' ';
+        else s++; // no decoding needed
+    }
+
+    if (t == '*') { // normalize spaces for non-cdata attributes
+        for (s = r; *s; s++) {
+            if ((l = strspn(s, " "))) memmove(s, s + l, strlen(s + l) + 1);
+            while (*s && *s != ' ') s++;
+        }
+        if (--s >= r && *s == ' ') *s = '\0'; // trim any trailing space
+    }
+    return r;
+}
+
+// called when parser finds start of new tag
+void dxml_open_tag(dxml_root_t root, char *name, char **attr)
+{
+    dxml_t xml = root->cur;
+    
+    if (xml->name) xml = dxml_add_child(xml, name, strlen(xml->txt));
+    else xml->name = name; // first open tag
+
+    xml->attr = attr;
+    root->cur = xml; // update tag insertion point
+}
+
+// called when parser finds character content between open and closing tag
+void dxml_char_content(dxml_root_t root, char *s, size_t len, char t)
+{
+    dxml_t xml = root->cur;
+    char *m = s;
+    size_t l;
+
+    if (! xml || ! xml->name || ! len) return; // sanity check
+
+    s[len] = '\0'; // null terminate text (calling functions anticipate this)
+    len = strlen(s = dxml_decode(s, root->ent, t)) + 1;
+
+    if (! *(xml->txt)) xml->txt = s; // initial character content
+    else { // allocate our own memory and make a copy
+        xml->txt = (char*)((xml->flags & dxml_TXTM) // allocate some space
+                   ? realloc(xml->txt, (l = strlen(xml->txt)) + len)
+                   : strcpy((char*)malloc((l = strlen(xml->txt)) + len), xml->txt));
+        strcpy(xml->txt + l, s); // add new char content
+        if (s != m) free(s); // free s if it was malloced by dxml_decode()
+    }
+
+    if (xml->txt != m) dxml_set_flag(xml, dxml_TXTM);
+}
+
+// called when parser finds closing tag
+dxml_t dxml_close_tag(dxml_root_t root, char *name, char *s)
+{
+    if (! root->cur || ! root->cur->name || strcmp(name, root->cur->name))
+        return dxml_err(root, s, "unexpected closing tag </%s>", name);
+
+    root->cur = root->cur->parent;
+    return NULL;
+}
+
+// checks for circular entity references, returns non-zero if no circular
+// references are found, zero otherwise
+int dxml_ent_ok(char *name, char *s, char **ent)
+{
+    int i;
+
+    for (; ; s++) {
+        while (*s && *s != '&') s++; // find next entity reference
+        if (! *s) return 1;
+        if (! strncmp(s + 1, name, strlen(name))) return 0; // circular ref.
+        for (i = 0; ent[i] && strncmp(ent[i], s + 1, strlen(ent[i])); i += 2);
+        if (ent[i] && ! dxml_ent_ok(name, ent[i + 1], ent)) return 0;
+    }
+}
+
+// called when the parser finds a processing instruction
+void dxml_proc_inst(dxml_root_t root, char *s, size_t len)
+{
+    int i = 0, j = 1;
+    char *target = s;
+
+    s[len] = '\0'; // null terminate instruction
+    if (*(s += strcspn(s, dxml_WS))) {
+        *s = '\0'; // null terminate target
+        s += strspn(s + 1, dxml_WS) + 1; // skip whitespace after target
+    }
+
+    if (! strcmp(target, "xml")) { // <?xml ... ?>
+        if ((s = strstr(s, "standalone")) && ! strncmp(s + strspn(s + 10,
+            dxml_WS "='\"") + 10, "yes", 3)) root->standalone = 1;
+        return;
+    }
+
+    if (! root->pi[0]) *(root->pi = (char***)malloc(sizeof(char **))) = NULL; //first pi
+
+    while (root->pi[i] && strcmp(target, root->pi[i][0])) i++; // find target
+    if (! root->pi[i]) { // new target
+        root->pi = (char***)realloc(root->pi, sizeof(char **) * (i + 2));
+        root->pi[i] = (char**)malloc(sizeof(char *) * 3);
+        root->pi[i][0] = target;
+        root->pi[i][1] = (char *)(root->pi[i + 1] = NULL); // terminate pi list
+        root->pi[i][2] = strdup(""); // empty document position list
+    }
+
+    while (root->pi[i][j]) j++; // find end of instruction list for this target
+    root->pi[i] = (char**)realloc(root->pi[i], sizeof(char *) * (j + 3));
+    root->pi[i][j + 2] = (char*)realloc(root->pi[i][j + 1], j + 1);
+    strcpy(root->pi[i][j + 2] + j - 1, (root->xml.name) ? ">" : "<");
+    root->pi[i][j + 1] = NULL; // null terminate pi list for this target
+    root->pi[i][j] = s; // set instruction
+}
+
+// called when the parser finds an internal doctype subset
+short dxml_internal_dtd(dxml_root_t root, char *s, size_t len)
+{
+    char q, *c, *t, *n = NULL, *v, **ent, **pe;
+    int i, j;
+    
+    pe = (char**)memcpy(malloc(sizeof(dxml_NIL)), dxml_NIL, sizeof(dxml_NIL));
+
+    for (s[len] = '\0'; s; ) {
+        while (*s && *s != '<' && *s != '%') s++; // find next declaration
+
+        if (! *s) break;
+        else if (! strncmp(s, "<!ENTITY", 8)) { // parse entity definitions
+            c = s += strspn(s + 8, dxml_WS) + 8; // skip white space separator
+            n = s + strspn(s, dxml_WS "%"); // find name
+            *(s = n + strcspn(n, dxml_WS)) = ';'; // append ; to name
+
+            v = s + strspn(s + 1, dxml_WS) + 1; // find value
+            if ((q = *(v++)) != '"' && q != '\'') { // skip externals
+                s = strchr(s, '>');
+                continue;
+            }
+
+            for (i = 0, ent = (*c == '%') ? pe : root->ent; ent[i]; i++);
+            ent = (char**)realloc(ent, (i + 3) * sizeof(char *)); // space for next ent
+            if (*c == '%') pe = ent;
+            else root->ent = ent;
+
+            *(++s) = '\0'; // null terminate name
+            if ((s = strchr(v, q))) *(s++) = '\0'; // null terminate value
+            ent[i + 1] = dxml_decode(v, pe, '%'); // set value
+            ent[i + 2] = NULL; // null terminate entity list
+            if (! dxml_ent_ok(n, ent[i + 1], ent)) { // circular reference
+                if (ent[i + 1] != v) free(ent[i + 1]);
+                dxml_err(root, v, "circular entity declaration &%s", n);
+                break;
+            }
+            else ent[i] = n; // set entity name
+        }
+        else if (! strncmp(s, "<!ATTLIST", 9)) { // parse default attributes
+            t = s + strspn(s + 9, dxml_WS) + 9; // skip whitespace separator
+            if (! *t) { dxml_err(root, t, "unclosed <!ATTLIST"); break; }
+            if (*(s = t + strcspn(t, dxml_WS ">")) == '>') continue;
+            else *s = '\0'; // null terminate tag name
+            for (i = 0; root->attr[i] && strcmp(n, root->attr[i][0]); i++);
+
+            while (*(n = ++s + strspn(s, dxml_WS)) && *n != '>') {
+                if (*(s = n + strcspn(n, dxml_WS))) *s = '\0'; // attr name
+                else { dxml_err(root, t, "malformed <!ATTLIST"); break; }
+
+                s += strspn(s + 1, dxml_WS) + 1; // find next token
+                c = strdup((strncmp(s, "CDATA", 5)) ? "*" : " "); // is it cdata?
+                if (! strncmp(s, "NOTATION", 8))
+                    s += strspn(s + 8, dxml_WS) + 8;
+                s = (*s == '(') ? strchr(s, ')') : s + strcspn(s, dxml_WS);
+                if (! s) { dxml_err(root, t, "malformed <!ATTLIST"); break; }
+
+                s += strspn(s, dxml_WS ")"); // skip white space separator
+                if (! strncmp(s, "#FIXED", 6))
+                    s += strspn(s + 6, dxml_WS) + 6;
+                if (*s == '#') { // no default value
+                    s += strcspn(s, dxml_WS ">") - 1;
+                    if (*c == ' ') continue; // cdata is default, nothing to do
+                    v = NULL;
+                }
+                else if ((*s == '"' || *s == '\'')  &&  // default value
+                         (s = strchr(v = s + 1, *s))) *s = '\0';
+                else { dxml_err(root, t, "malformed <!ATTLIST"); break; }
+
+                if (! root->attr[i]) { // new tag name
+                    root->attr = (char***)((! i) ? malloc(2 * sizeof(char **))
+                                       : realloc(root->attr,
+                                                 (i + 2) * sizeof(char **)));
+                    root->attr[i] = (char**)malloc(2 * sizeof(char *));
+                    root->attr[i][0] = t; // set tag name
+                    root->attr[i][1] = (char *)(root->attr[i + 1] = NULL);
+                }
+
+                for (j = 1; root->attr[i][j]; j += 3); // find end of list
+                root->attr[i] = (char**)realloc(root->attr[i],
+                                        (j + 4) * sizeof(char *));
+
+                root->attr[i][j + 3] = NULL; // null terminate list
+                root->attr[i][j + 2] = c; // is it cdata?
+                root->attr[i][j + 1] = (v) ? dxml_decode(v, root->ent, *c)
+                                           : NULL;
+                root->attr[i][j] = n; // attribute name 
+            }
+        }
+        else if (! strncmp(s, "<!--", 4)) s = strstr(s + 4, "-->"); // comments
+        else if (! strncmp(s, "<?", 2)) { // processing instructions
+            if ((s = strstr(c = s + 2, "?>")))
+                dxml_proc_inst(root, c, s++ - c);
+        }
+        else if (*s == '<') s = strchr(s, '>'); // skip other declarations
+        else if (*(s++) == '%' && ! root->standalone) break;
+    }
+
+    free(pe);
+    return ! *root->err;
+}
+
+// Converts a UTF-16 string to UTF-8. Returns a new string that must be freed
+// or NULL if no conversion was needed.
+char *dxml_str2utf8(char **s, size_t *len)
+{
+    char *u;
+    size_t l = 0, sl, max = *len;
+    long c, d;
+    int b, be = (**s == '\xFE') ? 1 : (**s == '\xFF') ? 0 : -1;
+
+    if (be == -1) return NULL; // not UTF-16
+
+    u = (char*)malloc(max);
+    for (sl = 2; sl < *len - 1; sl += 2) {
+        c = (be) ? (((*s)[sl] & 0xFF) << 8) | ((*s)[sl + 1] & 0xFF)  //UTF-16BE
+                 : (((*s)[sl + 1] & 0xFF) << 8) | ((*s)[sl] & 0xFF); //UTF-16LE
+        if (c >= 0xD800 && c <= 0xDFFF && (sl += 2) < *len - 1) { // high-half
+            d = (be) ? (((*s)[sl] & 0xFF) << 8) | ((*s)[sl + 1] & 0xFF)
+                     : (((*s)[sl + 1] & 0xFF) << 8) | ((*s)[sl] & 0xFF);
+            c = (((c & 0x3FF) << 10) | (d & 0x3FF)) + 0x10000;
+        }
+
+        while (l + 6 > max) u = (char*)realloc(u, max += dxml_BUFSIZE);
+        if (c < 0x80) u[l++] = c; // US-ASCII subset
+        else { // multi-byte UTF-8 sequence
+            for (b = 0, d = c; d; d /= 2) b++; // bits in c
+            b = (b - 2) / 5; // bytes in payload
+            u[l++] = (0xFF << (7 - b)) | (c >> (6 * b)); // head
+            while (b) u[l++] = 0x80 | ((c >> (6 * --b)) & 0x3F); // payload
+        }
+    }
+    return *s = (char*)realloc(u, *len = l);
+}
+
+// frees a tag attribute list
+void dxml_free_attr(char **attr) {
+    int i = 0;
+    char *m;
+    
+    if (! attr || attr == dxml_NIL) return; // nothing to free
+    while (attr[i]) i += 2; // find end of attribute list
+    m = attr[i + 1]; // list of which names and values are malloced
+    for (i = 0; m[i]; i++) {
+        if (m[i] & dxml_NAMEM) free(attr[i * 2]);
+        if (m[i] & dxml_TXTM) free(attr[(i * 2) + 1]);
+    }
+    free(m);
+    free(attr);
+}
+
+// parse the given xml string and return an dxml structure
+dxml_t dxml_parse_str(char *s, size_t len)
+{
+    dxml_root_t root = (dxml_root_t)dxml_new(NULL);
+    char q, e, *d, **attr, **a = NULL; // initialize a to avoid compile warning
+    int l, i, j;
+
+    root->m = s;
+    if (! len) return dxml_err(root, NULL, "root tag missing");
+    root->u = dxml_str2utf8(&s, &len); // convert utf-16 to utf-8
+    root->e = (root->s = s) + len; // record start and end of work area
+    
+    e = s[len - 1]; // save end char
+    s[len - 1] = '\0'; // turn end char into null terminator
+
+    while (*s && *s != '<') s++; // find first tag
+    if (! *s) return dxml_err(root, s, "root tag missing");
+
+    for (; ; ) {
+        attr = (char **)dxml_NIL;
+        d = ++s;
+        
+        if (isalpha(*s) || *s == '_' || *s == ':' || *s < '\0') { // new tag
+            if (! root->cur)
+                return dxml_err(root, d, "markup outside of root element");
+
+            s += strcspn(s, dxml_WS "/>");
+            while (isspace(*s)) *(s++) = '\0'; // null terminate tag name
+  
+            if (*s && *s != '/' && *s != '>') // find tag in default attr list
+                for (i = 0; (a = root->attr[i]) && strcmp(a[0], d); i++);
+
+            for (l = 0; *s && *s != '/' && *s != '>'; l += 2) { // new attrib
+                attr = (char**)((l) ? realloc(attr, (l + 4) * sizeof(char *))
+                           : malloc(4 * sizeof(char *))); // allocate space
+                attr[l + 3] = (char*)((l) ? realloc(attr[l + 1], (l / 2) + 2)
+                                  : malloc(2)); // mem for list of maloced vals
+                strcpy(attr[l + 3] + (l / 2), " "); // value is not malloced
+                attr[l + 2] = NULL; // null terminate list
+                attr[l + 1] = ""; // temporary attribute value
+                attr[l] = s; // set attribute name
+
+                s += strcspn(s, dxml_WS "=/>");
+                if (*s == '=' || isspace(*s)) { 
+                    *(s++) = '\0'; // null terminate tag attribute name
+                    q = *(s += strspn(s, dxml_WS "="));
+                    if (q == '"' || q == '\'') { // attribute value
+                        attr[l + 1] = ++s;
+                        while (*s && *s != q) s++;
+                        if (*s) *(s++) = '\0'; // null terminate attribute val
+                        else {
+                            dxml_free_attr(attr);
+                            return dxml_err(root, d, "missing %c", q);
+                        }
+
+                        for (j = 1; a && a[j] && strcmp(a[j], attr[l]); j +=3);
+                        attr[l + 1] = dxml_decode(attr[l + 1], root->ent, (a
+                                                   && a[j]) ? *a[j + 2] : ' ');
+                        if (attr[l + 1] < d || attr[l + 1] > s)
+                            attr[l + 3][l / 2] = dxml_TXTM; // value malloced
+                    }
+                }
+                while (isspace(*s)) s++;
+            }
+
+            if (*s == '/') { // self closing tag
+                *(s++) = '\0';
+                if ((*s && *s != '>') || (! *s && e != '>')) {
+                    if (l) dxml_free_attr(attr);
+                    return dxml_err(root, d, "missing >");
+                }
+                dxml_open_tag(root, d, attr);
+                dxml_close_tag(root, d, s);
+            }
+            else if ((q = *s) == '>' || (! *s && e == '>')) { // open tag
+                *s = '\0'; // temporarily null terminate tag name
+                dxml_open_tag(root, d, attr);
+                *s = q;
+            }
+            else {
+                if (l) dxml_free_attr(attr);
+                return dxml_err(root, d, "missing >"); 
+            }
+        }
+        else if (*s == '/') { // close tag
+            s += strcspn(d = s + 1, dxml_WS ">") + 1;
+            if (! (q = *s) && e != '>') return dxml_err(root, d, "missing >");
+            *s = '\0'; // temporarily null terminate tag name
+            if (dxml_close_tag(root, d, s)) return &root->xml;
+            if (isspace(*s = q)) s += strspn(s, dxml_WS);
+        }
+        else if (! strncmp(s, "!--", 3)) { // xml comment
+            if (! (s = strstr(s + 3, "--")) || (*(s += 2) != '>' && *s) ||
+                (! *s && e != '>')) return dxml_err(root, d, "unclosed <!--");
+        }
+        else if (! strncmp(s, "![CDATA[", 8)) { // cdata
+            if ((s = strstr(s, "]]>")))
+                dxml_char_content(root, d + 8, (s += 2) - d - 10, 'c');
+            else return dxml_err(root, d, "unclosed <![CDATA[");
+        }
+        else if (! strncmp(s, "!DOCTYPE", 8)) { // dtd
+            for (l = 0; *s && ((! l && *s != '>') || (l && (*s != ']' || 
+                 *(s + strspn(s + 1, dxml_WS) + 1) != '>')));
+                 l = (*s == '[') ? 1 : l) s += strcspn(s + 1, "[]>") + 1;
+            if (! *s && e != '>')
+                return dxml_err(root, d, "unclosed <!DOCTYPE");
+            d = (l) ? strchr(d, '[') + 1 : d;
+            if (l && ! dxml_internal_dtd(root, d, s++ - d)) return &root->xml;
+        }
+        else if (*s == '?') { // <?...?> processing instructions
+            do { s = strchr(s, '?'); } while (s && *(++s) && *s != '>');
+            if (! s || (! *s && e != '>')) 
+                return dxml_err(root, d, "unclosed <?");
+            else dxml_proc_inst(root, d + 1, s - d - 2);
+        }
+        else return dxml_err(root, d, "unexpected <");
+        
+        if (! s || ! *s) break;
+        *s = '\0';
+        d = ++s;
+        if (*s && *s != '<') { // tag character content
+            while (*s && *s != '<') s++;
+            if (*s) dxml_char_content(root, d, s - d, '&');
+            else break;
+        }
+        else if (! *s) break;
+    }
+
+    if (! root->cur) return &root->xml;
+    else if (! root->cur->name) return dxml_err(root, d, "root tag missing");
+    else return dxml_err(root, d, "unclosed tag <%s>", root->cur->name);
+}
+
+// Wrapper for dxml_parse_str() that accepts a file stream. Reads the entire
+// stream into memory and then parses it. For xml files, use dxml_parse_file()
+// or dxml_parse_fd()
+dxml_t dxml_parse_fp(FILE *fp)
+{
+    dxml_root_t root;
+    size_t l, len = 0;
+    char *s;
+
+    if (! (s = (char*)malloc(dxml_BUFSIZE))) return NULL;
+    do {
+        len += (l = fread((s + len), 1, dxml_BUFSIZE, fp));
+        if (l == dxml_BUFSIZE) s = (char*)realloc(s, len + dxml_BUFSIZE);
+    } while (s && l == dxml_BUFSIZE);
+
+    if (! s) return NULL;
+    root = (dxml_root_t)dxml_parse_str(s, len);
+    root->len = -1; // so we know to free s in dxml_free()
+    return &root->xml;
+}
+//
+//// A wrapper for dxml_parse_str() that accepts a file descriptor. First
+//// attempts to mem map the file. Failing that, reads the file into memory.
+//// Returns NULL on failure.
+//dxml_t dxml_parse_fd(int fd)
+//{
+//    dxml_root_t root;
+//    struct stat st;
+//    size_t l;
+//    void *m;
+//
+//    if (fd < 0) return NULL;
+//    fstat(fd, &st);
+//
+//#ifndef dxml_NOMMAP
+//    l = (st.st_size + sysconf(_SC_PAGESIZE) - 1) & ~(sysconf(_SC_PAGESIZE) -1);
+//    if ((m = mmap(NULL, l, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0)) !=
+//        MAP_FAILED) {
+//        madvise(m, l, MADV_SEQUENTIAL); // optimize for sequential access
+//        root = (dxml_root_t)dxml_parse_str(m, st.st_size);
+//        madvise(m, root->len = l, MADV_NORMAL); // put it back to normal
+//    }
+//    else { // mmap failed, read file into memory
+//#endif // dxml_NOMMAP
+//        l = read(fd, m = malloc(st.st_size), st.st_size);
+//        root = (dxml_root_t)dxml_parse_str((char*)m, l);
+//        root->len = -1; // so we know to free s in dxml_free()
+//#ifndef dxml_NOMMAP
+//    }
+//#endif // dxml_NOMMAP
+//    return &root->xml;
+//}
+
+// Encodes ampersand sequences appending the results to *dst, reallocating *dst
+// if length excedes max. a is non-zero for attribute encoding. Returns *dst
+char *dxml_ampencode(const char *s, size_t len, char **dst, size_t *dlen,
+                      size_t *max, short a)
+{
+    const char *e;
+    
+    for (e = s + len; s != e; s++) {
+        while (*dlen + 10 > *max) *dst = (char*)realloc(*dst, *max += dxml_BUFSIZE);
+
+        switch (*s) {
+        case '\0': return *dst;
+        case '&': *dlen += sprintf(*dst + *dlen, "&amp;"); break;
+        case '<': *dlen += sprintf(*dst + *dlen, "&lt;"); break;
+        case '>': *dlen += sprintf(*dst + *dlen, "&gt;"); break;
+        case '"': *dlen += sprintf(*dst + *dlen, (a) ? "&quot;" : "\""); break;
+        case '\n': *dlen += sprintf(*dst + *dlen, (a) ? "&#xA;" : "\n"); break;
+        case '\t': *dlen += sprintf(*dst + *dlen, (a) ? "&#x9;" : "\t"); break;
+        case '\r': *dlen += sprintf(*dst + *dlen, "&#xD;"); break;
+        default: (*dst)[(*dlen)++] = *s;
+        }
+    }
+    return *dst;
+}
+
+// Recursively converts each tag to xml appending it to *s. Reallocates *s if
+// its length excedes max. start is the location of the previous tag in the
+// parent tag's character content. Returns *s.
+char *dxml_toxml_r(dxml_t xml, char **s, size_t *len, size_t *max,
+                    size_t start, char ***attr)
+{
+    int i, j;
+    char *txt = (xml->parent) ? xml->parent->txt : strdup("");
+    size_t off = 0;
+
+    // parent character content up to this tag
+    *s = dxml_ampencode(txt + start, xml->off - start, s, len, max, 0);
+
+    while (*len + strlen(xml->name) + 4 > *max) // reallocate s
+        *s = (char*)realloc(*s, *max += dxml_BUFSIZE);
+
+    *len += sprintf(*s + *len, "<%s", xml->name); // open tag
+    for (i = 0; xml->attr[i]; i += 2) { // tag attributes
+        if (dxml_attr(xml, xml->attr[i]) != xml->attr[i + 1]) continue;
+        while (*len + strlen(xml->attr[i]) + 7 > *max) // reallocate s
+            *s = (char*)realloc(*s, *max += dxml_BUFSIZE);
+
+        *len += sprintf(*s + *len, " %s=\"", xml->attr[i]);
+        dxml_ampencode(xml->attr[i + 1], -1, s, len, max, 1);
+        *len += sprintf(*s + *len, "\"");
+    }
+
+    for (i = 0; attr[i] && strcmp(attr[i][0], xml->name); i++);
+    for (j = 1; attr[i] && attr[i][j]; j += 3) { // default attributes
+        if (! attr[i][j + 1] || dxml_attr(xml, attr[i][j]) != attr[i][j + 1])
+            continue; // skip duplicates and non-values
+        while (*len + strlen(attr[i][j]) + 7 > *max) // reallocate s
+            *s = (char*)realloc(*s, *max += dxml_BUFSIZE);
+
+        *len += sprintf(*s + *len, " %s=\"", attr[i][j]);
+        dxml_ampencode(attr[i][j + 1], -1, s, len, max, 1);
+        *len += sprintf(*s + *len, "\"");
+    }
+    *len += sprintf(*s + *len, ">");
+
+    *s = (xml->child) ? dxml_toxml_r(xml->child, s, len, max, 0, attr) //child
+                      : dxml_ampencode(xml->txt, -1, s, len, max, 0);  //data
+    
+    while (*len + strlen(xml->name) + 4 > *max) // reallocate s
+        *s = (char*)realloc(*s, *max += dxml_BUFSIZE);
+
+    *len += sprintf(*s + *len, "</%s>", xml->name); // close tag
+
+    while (txt[off] && off < xml->off) off++; // make sure off is within bounds
+    return (xml->ordered) ? dxml_toxml_r(xml->ordered, s, len, max, off, attr)
+                          : dxml_ampencode(txt + off, -1, s, len, max, 0);
+}
+
+// Converts an dxml structure back to xml. Returns a string of xml data that
+// must be freed.
+char *dxml_toxml(dxml_t xml)
+{
+    dxml_t p = (xml) ? xml->parent : NULL, o = (xml) ? xml->ordered : NULL;
+    dxml_root_t root = (dxml_root_t)xml;
+    size_t len = 0, max = dxml_BUFSIZE;
+    char *s = strcpy((char*)malloc(max), ""), *t, *n;
+    int i, j, k;
+
+    if (! xml || ! xml->name) return (char*)realloc(s, len + 1);
+    while (root->xml.parent) root = (dxml_root_t)root->xml.parent; // root tag
+
+    for (i = 0; ! p && root->pi[i]; i++) { // pre-root processing instructions
+        for (k = 2; root->pi[i][k - 1]; k++);
+        for (j = 1; (n = root->pi[i][j]); j++) {
+            if (root->pi[i][k][j - 1] == '>') continue; // not pre-root
+            while (len + strlen(t = root->pi[i][0]) + strlen(n) + 7 > max)
+                s = (char*)realloc(s, max += dxml_BUFSIZE);
+            len += sprintf(s + len, "<?%s%s%s?>\n", t, *n ? " " : "", n);
+        }
+    }
+
+    xml->parent = xml->ordered = NULL;
+    s = dxml_toxml_r(xml, &s, &len, &max, 0, root->attr);
+    xml->parent = p;
+    xml->ordered = o;
+
+    for (i = 0; ! p && root->pi[i]; i++) { // post-root processing instructions
+        for (k = 2; root->pi[i][k - 1]; k++);
+        for (j = 1; (n = root->pi[i][j]); j++) {
+            if (root->pi[i][k][j - 1] == '<') continue; // not post-root
+            while (len + strlen(t = root->pi[i][0]) + strlen(n) + 7 > max)
+                s = (char*)realloc(s, max += dxml_BUFSIZE);
+            len += sprintf(s + len, "\n<?%s%s%s?>", t, *n ? " " : "", n);
+        }
+    }
+    return (char*)realloc(s, len + 1);
+}
+
+// free the memory allocated for the dxml structure
+void dxml_free(dxml_t xml)
+{
+    dxml_root_t root = (dxml_root_t)xml;
+    int i, j;
+    char **a, *s;
+
+    if (! xml) return;
+    dxml_free(xml->child);
+    dxml_free(xml->ordered);
+
+    if (! xml->parent) { // free root tag allocations
+        for (i = 10; root->ent[i]; i += 2) // 0 - 9 are default entites (<>&"')
+            if ((s = root->ent[i + 1]) < root->s || s > root->e) free(s);
+        free(root->ent); // free list of general entities
+
+        for (i = 0; (a = root->attr[i]); i++) {
+            for (j = 1; a[j++]; j += 2) // free malloced attribute values
+                if (a[j] && (a[j] < root->s || a[j] > root->e)) free(a[j]);
+            free(a);
+        }
+        if (root->attr[0]) free(root->attr); // free default attribute list
+
+        for (i = 0; root->pi[i]; i++) {
+            for (j = 1; root->pi[i][j]; j++);
+            free(root->pi[i][j + 1]);
+            free(root->pi[i]);
+        }            
+        if (root->pi[0]) free(root->pi); // free processing instructions
+
+        if (root->len == -1) free(root->m); // malloced xml data
+#ifndef dxml_NOMMAP
+        else if (root->len) munmap(root->m, root->len); // mem mapped xml data
+#endif // dxml_NOMMAP
+        if (root->u) free(root->u); // utf8 conversion
+    }
+
+    dxml_free_attr(xml->attr); // tag attributes
+    if ((xml->flags & dxml_TXTM)) free(xml->txt); // character content
+    if ((xml->flags & dxml_NAMEM)) free(xml->name); // tag name
+    free(xml);
+}
+
+// return parser error message or empty string if none
+const char *dxml_error(dxml_t xml)
+{
+    while (xml && xml->parent) xml = xml->parent; // find root tag
+    return (xml) ? ((dxml_root_t)xml)->err : "";
+}
+
+// returns a new empty dxml structure with the given root tag name
+dxml_t dxml_new(const char *name)
+{
+    static char *ent[] = { "lt;", "&#60;", "gt;", "&#62;", "quot;", "&#34;",
+                           "apos;", "&#39;", "amp;", "&#38;", NULL };
+    dxml_root_t root = (dxml_root_t)memset(malloc(sizeof(struct dxml_root)), 
+                                             '\0', sizeof(struct dxml_root));
+    root->xml.name = (char *)name;
+    root->cur = &root->xml;
+    strcpy(root->err, root->xml.txt = "");
+    root->ent = (char**)memcpy(malloc(sizeof(ent)), ent, sizeof(ent));
+    root->attr = root->pi = (char ***)(root->xml.attr = dxml_NIL);
+    return &root->xml;
+}
+
+// inserts an existing tag into an dxml structure
+dxml_t dxml_insert(dxml_t xml, dxml_t dest, size_t off)
+{
+    dxml_t cur, prev, head;
+
+    xml->next = xml->sibling = xml->ordered = NULL;
+    xml->off = off;
+    xml->parent = dest;
+
+    if ((head = dest->child)) { // already have sub tags
+        if (head->off <= off) { // not first subtag
+            for (cur = head; cur->ordered && cur->ordered->off <= off;
+                 cur = cur->ordered);
+            xml->ordered = cur->ordered;
+            cur->ordered = xml;
+        }
+        else { // first subtag
+            xml->ordered = head;
+            dest->child = xml;
+        }
+
+        for (cur = head, prev = NULL; cur && strcmp(cur->name, xml->name);
+             prev = cur, cur = cur->sibling); // find tag type
+        if (cur && cur->off <= off) { // not first of type
+            while (cur->next && cur->next->off <= off) cur = cur->next;
+            xml->next = cur->next;
+            cur->next = xml;
+        }
+        else { // first tag of this type
+            if (prev && cur) prev->sibling = cur->sibling; // remove old first
+            xml->next = cur; // old first tag is now next
+            for (cur = head, prev = NULL; cur && cur->off <= off;
+                 prev = cur, cur = cur->sibling); // new sibling insert point
+            xml->sibling = cur;
+            if (prev) prev->sibling = xml;
+        }
+    }
+    else dest->child = xml; // only sub tag
+
+    return xml;
+}
+
+// Adds a child tag. off is the offset of the child tag relative to the start
+// of the parent tag's character content. Returns the child tag.
+dxml_t dxml_add_child(dxml_t xml, const char *name, size_t off)
+{
+    dxml_t child;
+
+    if (! xml) return NULL;
+    child = (dxml_t)memset(malloc(sizeof(struct dxml)), '\0',
+                            sizeof(struct dxml));
+    child->name = (char *)name;
+    child->attr = dxml_NIL;
+    child->txt = "";
+
+    return dxml_insert(child, xml, off);
+}
+
+// sets the character content for the given tag and returns the tag
+dxml_t dxml_set_txt(dxml_t xml, const char *txt)
+{
+    if (! xml) return NULL;
+    if (xml->flags & dxml_TXTM) free(xml->txt); // existing txt was malloced
+    xml->flags &= ~dxml_TXTM;
+    xml->txt = (char *)txt;
+    return xml;
+}
+
+// Sets the given tag attribute or adds a new attribute if not found. A value
+// of NULL will remove the specified attribute. Returns the tag given.
+dxml_t dxml_set_attr(dxml_t xml, const char *name, const char *value)
+{
+    int l = 0, c;
+
+    if (! xml) return NULL;
+    while (xml->attr[l] && strcmp(xml->attr[l], name)) l += 2;
+    if (! xml->attr[l]) { // not found, add as new attribute
+        if (! value) return xml; // nothing to do
+        if (xml->attr == dxml_NIL) { // first attribute
+            xml->attr = (char**)malloc(4 * sizeof(char *));
+            xml->attr[1] = strdup(""); // empty list of malloced names/vals
+        }
+        else xml->attr = (char**)realloc(xml->attr, (l + 4) * sizeof(char *));
+
+        xml->attr[l] = (char *)name; // set attribute name
+        xml->attr[l + 2] = NULL; // null terminate attribute list
+        xml->attr[l + 3] = (char*)realloc(xml->attr[l + 1],
+                                   (c = strlen(xml->attr[l + 1])) + 2);
+        strcpy(xml->attr[l + 3] + c, " "); // set name/value as not malloced
+        if (xml->flags & dxml_DUP) xml->attr[l + 3][c] = dxml_NAMEM;
+    }
+    else if (xml->flags & dxml_DUP) free((char *)name); // name was strduped
+
+    for (c = l; xml->attr[c]; c += 2); // find end of attribute list
+    if (xml->attr[c + 1][l / 2] & dxml_TXTM) free(xml->attr[l + 1]); //old val
+    if (xml->flags & dxml_DUP) xml->attr[c + 1][l / 2] |= dxml_TXTM;
+    else xml->attr[c + 1][l / 2] &= ~dxml_TXTM;
+
+    if (value) xml->attr[l + 1] = (char *)value; // set attribute value
+    else { // remove attribute
+        if (xml->attr[c + 1][l / 2] & dxml_NAMEM) free(xml->attr[l]);
+        memmove(xml->attr + l, xml->attr + l + 2, (c - l + 2) * sizeof(char*));
+        xml->attr = (char**)realloc(xml->attr, (c + 2) * sizeof(char *));
+        memmove(xml->attr[c + 1] + (l / 2), xml->attr[c + 1] + (l / 2) + 1,
+                (c / 2) - (l / 2)); // fix list of which name/vals are malloced
+    }
+    xml->flags &= ~dxml_DUP; // clear strdup() flag
+    return xml;
+}
+
+// sets a flag for the given tag and returns the tag
+dxml_t dxml_set_flag(dxml_t xml, short flag)
+{
+    if (xml) xml->flags |= flag;
+    return xml;
+}
+
+// removes a tag along with its subtags without freeing its memory
+dxml_t dxml_cut(dxml_t xml)
+{
+    dxml_t cur;
+
+    if (! xml) return NULL; // nothing to do
+    if (xml->next) xml->next->sibling = xml->sibling; // patch sibling list
+
+    if (xml->parent) { // not root tag
+        cur = xml->parent->child; // find head of subtag list
+        if (cur == xml) xml->parent->child = xml->ordered; // first subtag
+        else { // not first subtag
+            while (cur->ordered != xml) cur = cur->ordered;
+            cur->ordered = cur->ordered->ordered; // patch ordered list
+
+            cur = xml->parent->child; // go back to head of subtag list
+            if (strcmp(cur->name, xml->name)) { // not in first sibling list
+                while (strcmp(cur->sibling->name, xml->name))
+                    cur = cur->sibling;
+                if (cur->sibling == xml) { // first of a sibling list
+                    cur->sibling = (xml->next) ? xml->next
+                                               : cur->sibling->sibling;
+                }
+                else cur = cur->sibling; // not first of a sibling list
+            }
+
+            while (cur->next && cur->next != xml) cur = cur->next;
+            if (cur->next) cur->next = cur->next->next; // patch next list
+        }        
+    }
+    xml->ordered = xml->sibling = xml->next = NULL;
+    return xml;
+}
+
+#ifdef dxml_TEST // test harness
+int main(int argc, char **argv)
+{
+    dxml_t xml;
+    char *s;
+    int i;
+
+    if (argc != 2) return fprintf(stderr, "usage: %s xmlfile\n", argv[0]);
+
+    xml = dxml_parse_file(argv[1]);
+    printf("%s\n", (s = dxml_toxml(xml)));
+    free(s);
+    i = fprintf(stderr, "%s", dxml_error(xml));
+    dxml_free(xml);
+    return (i) ? 1 : 0;
+}
+#endif // dxml_TEST