PWN-Hunter/android_external_toybox
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Add mv -x to atomically swap two files.

Browse Source 
No idea if Mac or FreeBSD has renameat2(), but glibc refusing to wrap a 10
year old Linux syscall without "#define hurd" is also ridiculous, so I wrapped
the syscall myself in portability.c.
This commit is contained in:
Rob Landley 2024-03-03 01:58:43 -06:00
parent cc67996f80
commit a2419ad52d
3 changed files with 35 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
lib/portability.c
View File

@ -732,3 +732,14 @@ int timer_settime_wrap(timer_t t, int flags, struct itimerspec *val,
return syscall(SYS_timer_settime, t, flags, val, old);
}
#endif
// Atomically swap two files
int rename_exchange(char *file1, char *file2)
{
#if defined(__linux__)
// 2 is RENAME_EXCHANGE
return syscall(SYS_renameat2, AT_FDCWD, file1, AT_FDCWD, file2, 2);
#else
return ENOSYS;
#endif
}

1
lib/portability.h
View File

@ -403,6 +403,7 @@ int dev_makedev(int major, int minor);
char *fs_type_name(struct statfs *statfs);
int get_block_device_size(int fd, unsigned long long *size);
int rename_exchange(char *file1, char *file2);
#ifdef __APPLE__
// Apple doesn't have POSIX timers; this is "just enough" for timeout(1).

37
toys/posix/cp.c
View File

@ -15,8 +15,8 @@
// options shared between mv/cp must be in same order (right to left)
// for FLAG macros to work out right in shared infrastructure.
USE_CP(NEWTOY(cp, "<1(preserve):;D(parents)RHLPprudaslvnF(remove-destination)fit:T[-HLPd][-niu][+Rr]", TOYFLAG_BIN))
USE_MV(NEWTOY(mv, "<1v(verbose)nF(remove-destination)fit:T[-ni]", TOYFLAG_BIN))
USE_CP(NEWTOY(cp, "<1(preserve):;D(parents)RHLPprudaslv(verbose)nF(remove-destination)fit:T[-HLPd][-niu][+Rr]", TOYFLAG_BIN))
USE_MV(NEWTOY(mv, "<1x(swap)v(verbose)nF(remove-destination)fit:T[-ni]", TOYFLAG_BIN))
USE_INSTALL(NEWTOY(install, "<1cdDp(preserve-timestamps)svt:m:o:g:", TOYFLAG_USR|TOYFLAG_BIN))
config CP
@ -31,7 +31,7 @@ config CP
-a Same as -dpr
-D Create leading dirs under DEST (--parents)
-d Don't dereference symlinks
-F Delete any existing destination file first (--remove-destination)
-F Delete any existing DEST first (--remove-destination)
-f Delete destination files we can't write to
-H Follow symlinks listed on command line
-i Interactive, prompt before overwriting existing DEST
@ -61,14 +61,16 @@ config MV
bool "mv"
default y
help
usage: mv [-finTv] [-t TARGET] SOURCE... [DEST]
usage: mv [-FfinTvx] [-t TARGET] SOURCE... [DEST]
-F Delete any existing DEST first (--remove-destination)
-f Force copy by deleting destination file
-i Interactive, prompt before overwriting existing DEST
-n No clobber (don't overwrite DEST)
-t Move to TARGET dir (no DEST)
-T DEST always treated as file, max 2 arguments
-v Verbose
-x Atomically exchange source/dest (--swap)
config INSTALL
bool "install"
@ -464,21 +466,28 @@ void cp_main(void)
}
}
void mv_main(void)
{
toys.optflags |= FLAG_d|FLAG_p|FLAG_r;
TT.pflags =~0;
cp_main();
}
// Export cp flags into install's flag context.
// Export cp's flags into mv and install flag context.
static inline int cp_flag_F(void) { return FLAG_F; }
static inline int cp_flag_p(void) { return FLAG_p; }
static inline int cp_flag_v(void) { return FLAG_v; }
static inline int cp_flag_dpr(void) { return FLAG_d|FLAG_p|FLAG_r; }
#define FOR_mv
#include <generated/flags.h>
void mv_main(void)
{
toys.optflags |= cp_flag_dpr();
TT.pflags =~0;
if (FLAG(x)) {
if (toys.optc != 2) error_exit("-x needs 2 args");
if (rename_exchange(toys.optargs[0], toys.optargs[1]))
perror_exit("-x %s %s", toys.optargs[0], toys.optargs[1]);
} else cp_main();
}
// Switch to install's flag context
#define FOR_install
#include <generated/flags.h>