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exhaustively check for errors

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This commit is contained in:
Connor Olding 2018-08-11 14:33:52 +02:00
parent 66f196db6b
commit 0ee4adcb09
1 changed files with 79 additions and 67 deletions
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146
compressor.c
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@ -1,7 +1,8 @@
//#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
//#include <assert.h>
typedef unsigned char u8;
typedef unsigned int u32;
@ -10,6 +11,21 @@ typedef unsigned int u32;
#define MAX(a, b) ((a) >= (b) ? (a) : (b))
#define PMOD(a, b) (((a) + (b)) % (b))
#ifdef _WIN32
#define FMT_SIZE "%Iu"
#else
#define FMT_SIZE "%zu"
#endif
#define lament(...) fprintf(stderr, __VA_ARGS__)
#define error_when(cond, ...) do { \
if ((cond) || errno) { \
lament(__VA_ARGS__); \
lament(": %s\n", strerror(errno)); \
goto error; \
} \
} while (0)
#define BUF_LEN 1024
#define MIN_LEN 3
#define MAX_LEN 66
@ -19,9 +35,9 @@ typedef unsigned int u32;
#define RW_OVERLAP 1
#endif
char *program_name;
long compress(const u8 *bufi, long size, u8 *bufo) {
// this function cannot fail.
// just ensure bufo points to enough memory to hold the compressed data.
u8 buf[BUF_LEN] = {0};
int buf_i = BUF_START;
@ -48,21 +64,21 @@ long compress(const u8 *bufi, long size, u8 *bufo) {
int buf_off = (match_i + match_len) % BUF_LEN;
#if RW_OVERLAP
if (overlap > 0 || (buf_off == buf_i && j != 0)) {
if (sub[overlap % j] != sub[match_len]) { break; }
if (sub[overlap % j] != sub[match_len]) break;
overlap++;
} else {
if (buf[buf_off] != sub[match_len]) { break; }
if (buf[buf_off] != sub[match_len]) break;
}
#else
if (buf_off == buf_i && j != 0) { break; }
if (buf[buf_off] != sub[match_len]) { break; }
if (buf_off == buf_i && j != 0) break;
if (buf[buf_off] != sub[match_len]) break;
#endif
match_len++;
if (match_len == MAX_LEN) { break; }
if (match_len == sub_len) { break; }
if (match_len == MAX_LEN) break;
if (match_len == sub_len) break;
}
if (match_len < MIN_LEN) { continue; }
if (match_len < MIN_LEN) continue;
if (match_len > best_len) {
best_i = match_i;
best_len = match_len;
@ -121,87 +137,83 @@ long compress(const u8 *bufi, long size, u8 *bufo) {
}
int compress_file(const char *fp) {
// TODO: better error handling.
// functions here that can fail:
// fclose
// fopen
// fseek
// ftell
// fwrite
// malloc
// calloc
// free?
FILE *f = NULL;
u8 *bufi = NULL;
u8 *bufo = NULL;
char fs_buf[4] = {0};
long size = 0;
long new_size = 0;
FILE *f = fopen(fp, "rb");
if (f == NULL) {
perror(program_name);
return 1;
errno = 0;
f = fopen(fp, "rb");
error_when(f == NULL, "Error opening file: %s", fp);
error_when(fseek(f, 0, SEEK_END) != 0, "Error seeking in file: %s", fp);
size = ftell(f);
error_when(size < 0, "Error telling in file: %s", fp);
error_when(fseek(f, 0, SEEK_SET) != 0, "Error seeking in file: %s", fp);
if (size > 0) {
bufi = (u8 *)malloc(size);
error_when(bufi == NULL, "Error allocating %li bytes", size);
error_when(fread(bufi, 1, size, f) != (size_t)size, "Error reading %li bytes from file: %s", size, fp);
}
fseek(f, 0, SEEK_END);
long size = ftell(f);
fseek(f, 0, SEEK_SET);
error_when(fclose(f) != 0, "Error closing file: %s", fp);
if (size == 0) {
return 0;
if (size > 0) {
// allocate enough for the worst case scenario.
size_t bufo_size = size * 9 / 8 + 8;
bufo = (u8 *)malloc(bufo_size);
error_when(bufo == NULL, "Error allocating " FMT_SIZE " bytes", bufo_size);
new_size = compress(bufi, size, bufo);
//assert(new_size > 0 && (size_t)new_size < bufo_size);
}
u8 *bufi = (u8 *)malloc(size);
if (bufi == NULL) {
fprintf(stderr, "failed to malloc %li bytes\n", size);
free(bufi);
return 2;
}
fread(bufi, 1, size, f);
fclose(f);
// allocate enough for the worst case scenario.
size_t bufo_size = size * 9 / 8 + 8;
u8 *bufo = (u8 *)malloc(bufo_size);
long new_size = compress(bufi, size, bufo);
free(bufi);
//assert(new_size > 0 && (size_t)new_size < bufo_size);
f = fopen(fp, "wb");
if (f == NULL) {
perror(program_name);
free(bufo);
return 3;
}
error_when(f == NULL, "Error opening file: %s", fp);
char fs_buf[4] = {0};
fs_buf[0] = (size >> 24) & 0xFF;
fs_buf[1] = (size >> 16) & 0xFF;
fs_buf[2] = (size >> 8) & 0xFF;
fs_buf[3] = size & 0xFF;
fwrite(fs_buf, 1, 4, f);
error_when(fwrite(fs_buf, 1, 4, f) != 4, "Error writing %i bytes to file: %s", 4, fp);
fwrite(bufo, 1, new_size, f);
fclose(f);
if (new_size > 0) {
error_when(fwrite(bufo, 1, new_size, f) != (size_t)new_size, "Error writing %i bytes to file: %s", 4, fp);
}
error_when(fclose(f) != 0, "Error closing file: %s", fp);
free(bufi);
free(bufo);
return 0;
error:
free(bufi);
free(bufo);
return 1;
}
int main(int argc, char *argv[]) {
if (argc <= 0 || argv == NULL || argv[0] == NULL) {
fprintf(stderr, "You've met with a terrible fate.\n");
exit(1);
lament("You've met with a terrible fate.\n");
return 1;
}
program_name = argv[0];
const char *name = argv[0];
if (argc == 1) {
fprintf(stderr, "usage: %s {file}\n", program_name);
exit(2);
lament("compressor: compress files in-place for Bomberman 64.\n");
lament("usage: %s {file}\n", name);
return 1;
} else if (argc == 2) {
const char *fp = argv[1];
int ret = compress_file(fp);
if (ret != 0) {
exit(ret + 3);
}
return ret;
} else {
fprintf(stderr, "too many arguments\n");
exit(3);
lament("Error: too many arguments\n");
lament("usage: %s {file}\n", name);
return 1;
}
}