forked from mirrors/nixpkgs
59 lines
1.5 KiB
C
59 lines
1.5 KiB
C
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// makeCWrapper /path/to/executable \
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--argv0 my-wrapper \
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--set-default MESSAGE HELLO \
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--prefix PATH : /usr/bin/ \
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--suffix PATH : /usr/local/bin/ \
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--add-flags "-x -y -z" \
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--set MESSAGE2 WORLD
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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char *concat3(char *x, char *y, char *z) {
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int xn = strlen(x);
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int yn = strlen(y);
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int zn = strlen(z);
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char *res = malloc(sizeof(*res)*(xn + yn + zn + 1));
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strncpy(res, x, xn);
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strncpy(res + xn, y, yn);
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strncpy(res + xn + yn, z, zn);
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res[xn + yn + zn] = '\0';
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return res;
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}
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void set_env_prefix(char *env, char *sep, char *val) {
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char *existing = getenv(env);
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if (existing) val = concat3(val, sep, existing);
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setenv(env, val, 1);
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if (existing) free(val);
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}
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void set_env_suffix(char *env, char *sep, char *val) {
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char *existing = getenv(env);
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if (existing) val = concat3(existing, sep, val);
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setenv(env, val, 1);
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if (existing) free(val);
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}
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int main(int argc, char **argv) {
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setenv("MESSAGE", "HELLO", 0);
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set_env_prefix("PATH", ":", "/usr/bin/");
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set_env_suffix("PATH", ":", "/usr/local/bin/");
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putenv("MESSAGE2=WORLD");
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char **argv_tmp = malloc(sizeof(*argv_tmp) * (4 + argc));
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argv_tmp[0] = argv[0];
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argv_tmp[1] = "-x";
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argv_tmp[2] = "-y";
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argv_tmp[3] = "-z";
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for (int i = 1; i < argc; ++i) {
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argv_tmp[3 + i] = argv[i];
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}
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argv_tmp[3 + argc] = NULL;
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argv = argv_tmp;
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argv[0] = "my-wrapper";
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return execv("/path/to/executable", argv);
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}
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