Merge branch 'gb/idx'
[git] / 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 1 on a successful substitution pass that fits in result,
48  * Returns 0 on a failed or overflowing substitution pass.
49  */
50
51 int interpolate(char *result, int reslen,
52                 const char *orig,
53                 const struct interp *interps, int ninterps)
54 {
55         const char *src = orig;
56         char *dest = result;
57         int newlen = 0;
58         const char *name, *value;
59         int namelen, valuelen;
60         int i;
61         char c;
62
63         memset(result, 0, reslen);
64
65         while ((c = *src) && newlen < reslen - 1) {
66                 if (c == '%') {
67                         /* Try to match an interpolation string. */
68                         for (i = 0; i < ninterps; i++) {
69                                 name = interps[i].name;
70                                 namelen = strlen(name);
71                                 if (strncmp(src, name, namelen) == 0) {
72                                         break;
73                                 }
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 < reslen - 1) {
82                                         /* Substitute. */
83                                         strncpy(dest, value, valuelen);
84                                         newlen += valuelen;
85                                         dest += valuelen;
86                                         src += namelen;
87                                 } else {
88                                         /* Something's not fitting. */
89                                         return 0;
90                                 }
91
92                         } else {
93                                 /* Skip bogus interpolation. */
94                                 *dest++ = *src++;
95                                 newlen++;
96                         }
97
98                 } else {
99                         /* Straight copy one non-interpolation character. */
100                         *dest++ = *src++;
101                         newlen++;
102                 }
103         }
104
105         return newlen < reslen - 1;
106 }