interpolate.c

   1 /*
   2  * Copyright 2006 Jon Loeliger
   3  */
   4
   5 #include <string.h>
   6
   7 #include "git-compat-util.h"
   8 #include "interpolate.h"
   9
  10
  11 void interp_set_entry(struct interp *table, int slot, const char *value)
  12 {
  13         char *oldval = table[slot].value;
  14         char *newval = NULL;
  15
  16         if (oldval)
  17                 free(oldval);
  18
  19         if (value)
  20                 newval = xstrdup(value);
  21
  22         table[slot].value = newval;
  23 }
  24
  25
  26 void interp_clear_table(struct interp *table, int ninterps)
  27 {
  28         int i;
  29
  30         for (i = 0; i < ninterps; i++) {
  31                 interp_set_entry(table, i, NULL);
  32         }
  33 }
  34
  35
  36 /*
  37  * Convert a NUL-terminated string in buffer orig
  38  * into the supplied buffer, result, whose length is reslen,
  39  * performing substitutions on %-named sub-strings from
  40  * the table, interps, with ninterps entries.
  41  *
  42  * Example interps:
  43  *    {
  44  *        { "%H", "example.org"},
  45  *        { "%port", "123"},
  46  *        { "%%", "%"},
  47  *    }
  48  *
  49  * Returns 1 on a successful substitution pass that fits in result,
  50  * Returns 0 on a failed or overflowing substitution pass.
  51  */
  52
  53 int interpolate(char *result, int reslen,
  54                 const char *orig,
  55                 const struct interp *interps, int ninterps)
  56 {
  57         const char *src = orig;
  58         char *dest = result;
  59         int newlen = 0;
  60         char *name, *value;
  61         int namelen, valuelen;
  62         int i;
  63         char c;
  64
  65         memset(result, 0, reslen);
  66
  67         while ((c = *src) && newlen < reslen - 1) {
  68                 if (c == '%') {
  69                         /* Try to match an interpolation string. */
  70                         for (i = 0; i < ninterps; i++) {
  71                                 name = interps[i].name;
  72                                 namelen = strlen(name);
  73                                 if (strncmp(src, name, namelen) == 0) {
  74                                         break;
  75                                 }
  76                         }
  77
  78                         /* Check for valid interpolation. */
  79                         if (i < ninterps) {
  80                                 value = interps[i].value;
  81                                 valuelen = strlen(value);
  82
  83                                 if (newlen + valuelen < reslen - 1) {
  84                                         /* Substitute. */
  85                                         strncpy(dest, value, valuelen);
  86                                         newlen += valuelen;
  87                                         dest += valuelen;
  88                                         src += namelen;
  89                                 } else {
  90                                         /* Something's not fitting. */
  91                                         return 0;
  92                                 }
  93
  94                         } else {
  95                                 /* Skip bogus interpolation. */
  96                                 *dest++ = *src++;
  97                                 newlen++;
  98                         }
  99
 100                 } else {
 101                         /* Straight copy one non-interpolation character. */
 102                         *dest++ = *src++;
 103                         newlen++;
 104                 }
 105         }
 106
 107         return newlen < reslen - 1;
 108 }