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/*
* readbyte.c -- read a byte from a given file, using open()/read() or fopen()/fread()
*
* Copyright (C) 2018 Martin Pitt <martin@piware.de>
*
* umockdev is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* umockdev is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#define writestr(s) assert(write(fd, s, strlen(s)) >= 0)
int
main(int argc, char **argv)
{
char buf;
if (argc < 2 || argc > 3) {
fprintf(stderr, "Usage: %s file [open|fopen]\n", argv[0]);
return 1;
}
if (argc == 2 || strcmp(argv[2], "open") == 0) {
int fd;
ssize_t len;
fd = open(argv[1], O_RDWR);
if (fd < 0) {
perror("open");
return 1;
}
len = read(fd, &buf, 1);
if (len < 0) {
perror("read");
return 1;
}
close(fd);
}
else if (strcmp(argv[2], "fopen") == 0) {
FILE *f;
size_t len;
f = fopen(argv[1], "rb");
if (f == NULL) {
perror("fopen");
return 1;
}
len = fread(&buf, 1, 1, f);
if (len != 1 && ferror(f) != 0) {
perror("fread");
return 1;
}
fclose(f);
}
else {
fprintf(stderr, "ERROR: Unknown mode %s\n", argv[2]);
return 1;
}
return 0;
}
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