interpolate.c

   1 /*
   2  * Copyright 2006 Jon Loeliger
   3  */
   4
   5 #include "git-compat-util.h"
   6 #include "interpolate.h"
   7
   8
   9 void interp_set_entry(struct interp *table, int slot, const char *value)
  10 {
  11         char *oldval = table[slot].value;
  12         char *newval = NULL;
  13
  14         if (oldval)
  15                 free(oldval);
  16
  17         if (value)
  18                 newval = xstrdup(value);
  19
  20         table[slot].value = newval;
  21 }
  22
  23
  24 void interp_clear_table(struct interp *table, int ninterps)
  25 {
  26         int i;
  27
  28         for (i = 0; i < ninterps; i++) {
  29                 interp_set_entry(table, i, NULL);
  30         }
  31 }
  32
  33
  34 /*
  35  * Convert a NUL-terminated string in buffer orig
  36  * into the supplied buffer, result, whose length is reslen,
  37  * performing substitutions on %-named sub-strings from
  38  * the table, interps, with ninterps entries.
  39  *
  40  * Example interps:
  41  *    {
  42  *        { "%H", "example.org"},
  43  *        { "%port", "123"},
  44  *        { "%%", "%"},
  45  *    }
  46  *
  47  * Returns 0 on a successful substitution pass that fits in result,
  48  * Returns a number of bytes needed to hold the full substituted
  49  * string otherwise.
  50  */
  51
  52 unsigned long interpolate(char *result, unsigned long reslen,
  53                 const char *orig,
  54                 const struct interp *interps, int ninterps)
  55 {
  56         const char *src = orig;
  57         char *dest = result;
  58         unsigned long newlen = 0;
  59         const char *name, *value;
  60         unsigned long namelen, valuelen;
  61         int i;
  62         char c;
  63
  64         memset(result, 0, reslen);
  65
  66         while ((c = *src)) {
  67                 if (c == '%') {
  68                         /* Try to match an interpolation string. */
  69                         for (i = 0; i < ninterps; i++) {
  70                                 name = interps[i].name;
  71                                 namelen = strlen(name);
  72                                 if (strncmp(src, name, namelen) == 0)
  73                                         break;
  74                         }
  75
  76                         /* Check for valid interpolation. */
  77                         if (i < ninterps) {
  78                                 value = interps[i].value;
  79                                 valuelen = strlen(value);
  80
  81                                 if (newlen + valuelen + 1 < reslen) {
  82                                         /* Substitute. */
  83                                         strncpy(dest, value, valuelen);
  84                                         dest += valuelen;
  85                                 }
  86                                 newlen += valuelen;
  87                                 src += namelen;
  88                                 continue;
  89                         }
  90                 }
  91                 /* Straight copy one non-interpolation character. */
  92                 if (newlen + 1 < reslen)
  93                         *dest++ = *src;
  94                 src++;
  95                 newlen++;
  96         }
  97
  98         if (newlen + 1 < reslen)
  99                 return 0;
 100         else
 101                 return newlen + 2;
 102 }