pkgs/build-support/expand-response-params/expand-response-params.c

   1 #include <assert.h>
   2 #include <ctype.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5 #include <string.h>
   6
   7 typedef struct { char *data; size_t len, cap; } String;
   8
   9 void resize(String *s, size_t len) {
  10     s->len = len;
  11     if (s->cap < s->len) {
  12         s->cap = s->len * 2;
  13         s->data = (char *)realloc(s->data, s->cap);
  14         assert(s->data);
  15     }
  16 }
  17
  18 void append(String *s, const char *data, size_t len) {
  19     resize(s, s->len + len);
  20     memcpy(s->data + s->len - len, data, len);
  21 }
  22
  23 typedef enum { space = 0, other = 1, backslash = 2, apostrophe = 3, quotation_mark = 4 } CharClass;
  24 typedef enum { outside, unq, unq_esc, sq, sq_esc, dq, dq_esc } State;
  25
  26 // current State -> CharClass -> next State
  27 const State transitions[][5] = {
  28     [outside] = {outside, unq, unq_esc, sq,  dq},
  29     [unq]     = {outside, unq, unq_esc, sq,  dq},
  30     [unq_esc] = {unq,     unq, unq,     unq, unq},
  31     [sq]      = {sq,      sq,  sq_esc,  unq, sq},
  32     [sq_esc]  = {sq,      sq,  sq,      sq,  sq},
  33     [dq]      = {dq,      dq,  dq_esc,  dq,  unq},
  34     [dq_esc]  = {dq,      dq,  dq,      dq,  dq},
  35 };
  36
  37 CharClass charClass(int c) {
  38     return c == '\\' ? backslash : c == '\'' ? apostrophe : c == '"' ? quotation_mark :
  39             isspace(c) ? space : other;
  40 }
  41
  42 // expandArg writes NULL-terminated expansions of `arg', a NULL-terminated
  43 // string, to stdout.  If arg does not begin with `@' or does not refer to a
  44 // file, it is written as is.  Otherwise the contents of the file are
  45 // recursively expanded.  On unexpected EOF in malformed response files an
  46 // incomplete final argument is written, even if it is empty, to parse like GCC.
  47 void expandArg(String *arg) {
  48     FILE *f;
  49     if (arg->data[0] != '@' || !(f = fopen(&arg->data[1], "r"))) {
  50         fwrite(arg->data, 1, arg->len, stdout);
  51         return;
  52     }
  53
  54     resize(arg, 0);
  55     State cur = outside;
  56     int c;
  57     do {
  58         c = fgetc(f);
  59         State next = transitions[cur][charClass(c)];
  60         if ((cur == unq && next == outside) || (cur != outside && c == EOF)) {
  61             append(arg, "", 1);
  62             expandArg(arg);
  63             resize(arg, 0);
  64         } else if (cur == unq_esc || cur == sq_esc || cur == dq_esc ||
  65                    (cur == outside ? next == unq : cur == next)) {
  66             char s = c;
  67             append(arg, &s, 1);
  68         }
  69         cur = next;
  70     } while (c != EOF);
  71
  72     fclose(f);
  73 }
  74
  75 int main(int argc, char **argv) {
  76     String arg = { 0 };
  77     while (*++argv) {
  78         resize(&arg, 0);
  79         append(&arg, *argv, strlen(*argv) + 1);
  80         expandArg(&arg);
  81     }
  82     free(arg.data);
  83     return EXIT_SUCCESS;
  84 }