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#define _GNU_SOURCE /* for RTLD_NEXT */
#include <assert.h>
#include <dlfcn.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
static FILE *fail;
static FILE *fail_read;
static FILE *fail_write;
static FILE *fail_close;
static int error;
static FILE * (*real_fopen)(const char *, const char *);
static int (*real_fclose)(FILE *);
static int (*real_ferror)(FILE *);
static void (*real_clearerr)(FILE *);
static char * (*real_fgets)(char *, int, FILE *);
static size_t (*real_fread)(void *, size_t, size_t, FILE *);
static size_t (*real_fwrite)(const void *, size_t, size_t, FILE *);
#define GET_REAL(sym) \
do { \
if (real_ ## sym == 0) { \
real_ ## sym = dlsym(RTLD_NEXT, #sym); \
assert(real_ ## sym != 0); \
} \
} while (0)
#define dbg_write(msg) (void)write(2, msg, sizeof(msg) - 1)
#define dbg() \
do { \
dbg_write("here: "); \
dbg_write(__func__); \
dbg_write("!\n"); \
} while (0)
FILE *fopen(const char *path, const char *mode) {
GET_REAL(fopen);
fail = fail_read = fail_write = fail_close = 0;
FILE *f = real_fopen(path, mode);
error = EIO;
if (strcmp(path, "fail_read") == 0) {
fail = fail_read = f;
} else if (strncmp(path, "fail_write", sizeof("fail_write") - 1) == 0) {
// Not that jq opens files for write anyways...
fail = fail_write = f;
if (strcmp(path, "fail_write_enospc") == 0)
error = ENOSPC;
} else if (strncmp(path, "fail_close", sizeof("fail_close") - 1) == 0) {
fail = fail_close = f;
if (strcmp(path, "fail_close_enospc") == 0)
error = ENOSPC;
}
return f;
}
int fclose(FILE *f) {
GET_REAL(fclose);
int res = real_fclose(f);
if (fail_close == f) {
fail = fail_read = fail_write = fail_close = 0;
return EOF;
}
return res;
}
char * fgets(char *buf, int len, FILE *f) {
GET_REAL(fgets);
char *res = real_fgets(buf, len, f);
if (fail_read == f)
return 0;
return res;
}
size_t fread(void *buf, size_t sz, size_t nemb, FILE *f) {
GET_REAL(fread);
size_t res = real_fread(buf, sz, nemb, f);
if (fail_read == f)
return 0;
return res;
}
size_t fwrite(const void *buf, size_t sz, size_t nemb, FILE *f) {
GET_REAL(fwrite);
size_t res = real_fwrite(buf, sz, nemb, f);
if (fail_write == f)
return 0;
return res;
}
int ferror(FILE *f) {
GET_REAL(ferror);
int res = real_ferror(f);
if (fail == f) {
errno = error;
return 1;
}
return res;
}
void clearerr(FILE *f) {
GET_REAL(clearerr);
real_clearerr(f);
if (fail == f) {
fail = fail_read = fail_write = fail_close = 0;
error = 0;
}
}
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