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/* trunc.c: Set the size of an existing file, or create a file of a
* specified size.
*
* Copyright (C) 2008 Micah J. Cowan
*
* Copying and distribution of this file, with or without modification,
* are permitted in any medium without royalty provided the copyright
* notice and this notice are preserved. */
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#define PROGRAM_NAME "trunc"
void
usage (FILE *f)
{
fputs (
PROGRAM_NAME " [-c] file sz\n\
\n\
Set the filesize of FILE to SIZE.\n\
\n\
-c: create FILE if it doesn't exist.\n\
\n\
Multiplier suffixes for SIZE (case-insensitive):\n\
k: SIZE * 1024\n\
m: SIZE * 1024 * 1024\n", f);
}
off_t
get_size (const char str[])
{
unsigned long val;
int suffix;
char *end;
errno = 0;
val = strtoul(str, &end, 10);
if (end == str)
{
fputs (PROGRAM_NAME ": size is not a number.\n", stderr);
usage (stderr);
exit (EXIT_FAILURE);
}
else if (errno == ERANGE
|| (unsigned long)(off_t)val != val)
{
fputs (PROGRAM_NAME ": size is out of range.\n", stderr);
exit (EXIT_FAILURE);
}
suffix = tolower ((unsigned char) end[0]);
if (suffix == 'k')
{
val *= 1024;
}
else if (suffix == 'm')
{
val *= 1024 * 1024;
}
return val;
}
int
main (int argc, char *argv[])
{
const char *fname;
const char *szstr;
off_t sz;
int create = 0;
int option;
int fd;
#ifdef ENABLE_NLS
/* Set the current locale. */
setlocale (LC_ALL, "");
/* Set the text message domain. */
bindtextdomain ("wget", LOCALEDIR);
textdomain ("wget");
#endif /* ENABLE_NLS */
/* Parse options. */
while ((option = getopt (argc, argv, "c")) != -1)
{
switch (option) {
case 'c':
create = 1;
break;
case '?':
fprintf (stderr, PROGRAM_NAME ": Unrecognized option `%c'.\n\n",
optopt);
usage (stderr);
exit (EXIT_FAILURE);
default:
/* We shouldn't reach here. */
abort();
}
}
if (argv[optind] == NULL
|| argv[optind+1] == NULL
|| argv[optind+2] != NULL)
{
usage (stderr);
exit (EXIT_FAILURE);
}
fname = argv[optind];
szstr = argv[optind+1];
sz = get_size(szstr);
if (create)
{
mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
fd = open(fname, O_WRONLY | O_CREAT, mode);
}
else
{
fd = open(fname, O_WRONLY);
}
if (fd == -1)
{
perror (PROGRAM_NAME ": open");
exit (EXIT_FAILURE);
}
if (ftruncate(fd, sz) == -1)
{
perror (PROGRAM_NAME ": truncate");
exit (EXIT_FAILURE);
}
if (close (fd) < 0)
{
perror (PROGRAM_NAME ": close");
exit (EXIT_FAILURE);
}
return 0;
}
|
