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// SPDX-License-Identifier: GPL-2.0-only
// SPDX-FileCopyrightText: 2012 Alexey Galakhov
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <stddef.h>
#include <errno.h>
#define DEFAULT_BUF_SIZE 8192
static int usage(const char* me)
{
printf("Usage: %s <input> <output> [<bufsize]\n", me);
return 1;
}
static void put32(uint8_t *ptr, uint32_t value)
{
ptr[0] = value & 0xFF;
ptr[1] = (value >> 8) & 0xFF;
ptr[2] = (value >> 16) & 0xFF;
ptr[3] = (value >> 24) & 0xFF;
}
static size_t safe_fread(void *buf, size_t len, FILE* file)
{
size_t rd = fread(buf, 1, len, file);
if (! rd) {
if (ferror(file))
fprintf(stderr, "Error reading file: %s\n", strerror(errno));
else
fprintf(stderr, "Unexpected end of file\n");
}
return rd;
}
static size_t safe_fwrite(const void *buf, size_t len, FILE* file)
{
size_t wr = fwrite(buf, 1, len, file);
if (wr != len) {
fprintf(stderr, "Error writing file: %s\n", strerror(errno));
return 0;
}
return wr;
}
static int process(FILE *input, FILE *output, uint8_t *buf, unsigned bufsize)
{
size_t rd;
unsigned i;
uint32_t cksum;
/* Read first chunk */
rd = safe_fread(buf + 16, bufsize - 16, input);
if (! rd)
return 4;
/* Calculate header */
put32(buf + 0, bufsize);
cksum = 0;
for (i = 16; i < bufsize; ++i)
cksum += (uint32_t)buf[i];
put32(buf + 8, cksum);
if (! safe_fwrite(buf, bufsize, output))
return 4;
/* Copy the rest of file */
while (! feof(input)) {
rd = safe_fread(buf, bufsize, input);
if (! rd)
return 4;
if (! safe_fwrite(buf, rd, output))
return 4;
}
return 0;
}
static int work(const char* me, const char *infile, const char *outfile, unsigned bufsize)
{
uint8_t *buf;
FILE *input;
FILE *output;
int ret;
if (bufsize < 512 || bufsize > 65536)
return usage(me);
buf = calloc(1, bufsize);
if (! buf) {
fprintf(stderr, "Unable to allocate %u bytes of memory\n", bufsize);
return 2;
}
input = fopen(infile, "r");
if (! input) {
fprintf(stderr, "Cannot open `%s' for reading\n", infile);
free(buf);
return 3;
}
output = fopen(outfile, "w");
if (! output) {
fprintf(stderr, "Cannot open `%s' for writing\n", outfile);
fclose(input);
free(buf);
return 3;
}
ret = process(input, output, buf, bufsize);
fclose(output);
fclose(input);
free(buf);
return ret;
}
int main(int argc, char** argv)
{
switch (argc) {
case 3:
return work(argv[0], argv[1], argv[2], DEFAULT_BUF_SIZE);
case 4:
return work(argv[0], argv[1], argv[2], atoi(argv[3]));
default:
return usage(argv[0]);
}
}
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