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/* truncate.c - set file length, extending sparsely if necessary
*
* Copyright 2011 Rob Landley <rob@landley.net>
USE_TRUNCATE(NEWTOY(truncate, "<1s:|c", TOYFLAG_BIN))
config TRUNCATE
bool "truncate"
default y
help
usage: truncate [-c] -s SIZE file...
Set length of file(s), extending sparsely if necessary.
-c Don't create file if it doesn't exist.
-s New size (with optional prefix and suffix)
SIZE prefix: + add, - subtract, < shrink to, > expand to,
/ block size rounding down, % block size rounding up
SIZE suffix: k=1024, m=1024^2, g=1024^3, t=1024^4, p=1024^5, e=1024^6
*/
#define FOR_truncate
#include "toys.h"
GLOBALS(
char *s;
long size;
int type;
)
static void do_truncate(int fd, char *name)
{
long long size;
if (fd<0) return;
if (TT.type == -1) size = TT.size;
else {
size = fdlength(fd);
if (TT.type<2) size += TT.size*(1-(2*TT.type));
else if (TT.type<4) {
if ((TT.type==3) ? size > TT.size : size < TT.size) size = TT.size;
} else {
size = (size+(TT.type-4)*(TT.size-1))/TT.size;
size *= TT.size;
}
}
if (ftruncate(fd, size)) perror_msg("'%s' to '%lld'", name, size);
}
void truncate_main(void)
{
int cr = !(toys.optflags&1);
if (-1 != (TT.type = stridx("+-<>/%", *TT.s))) TT.s++;
TT.size = atolx(TT.s);
// Create files with mask rwrwrw.
// Nonexistent files are only an error if we're supposed to create them.
loopfiles_rw(toys.optargs, O_WRONLY|O_CLOEXEC|(cr ? O_CREAT : 0), 0666, cr,
do_truncate);
}
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