63 lines
1.1 KiB
C
63 lines
1.1 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <alloca.h>
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#define MAX_LEN 1024
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#define SYSCONF_DIR "/etc"
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int open_sysconf(const char *, int, int);
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int main(void)
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{
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int fd = open_sysconf("/passwd", O_RDONLY, 0644);
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if (fd == -1) {
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perror("open");
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return -1;
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}
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int len;
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if ((len = lseek(fd, 0, SEEK_END)) == -1) {
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perror("lseek");
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return -1;
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}
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if (lseek(fd, 0, SEEK_SET) == -1) {
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perror("lseek");
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return -1;
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}
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char buffer[len + 1];
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memset(buffer, 0, sizeof(buffer));
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ssize_t ret;
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size_t bytes_read_total = 0;
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while (bytes_read_total < len && (ret = read(fd, buffer + bytes_read_total, len - bytes_read_total)) != 0) {
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if (ret == -1) {
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if (errno == EINTR) continue;
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perror("read");
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break;
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}
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bytes_read_total += ret;
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}
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buffer[bytes_read_total] = '\0';
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printf("%s", buffer);
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close(fd);
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return 0;
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}
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int open_sysconf(const char *file, int flags, int mode)
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{
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const char *etc = SYSCONF_DIR;
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char *name = alloca(strlen(etc) + strlen(file) + 1);
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strcpy(name, etc);
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strcat(name, file);
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return open(name, flags, mode);
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}
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