From f23996b445422bdc79b4a16da63c740ae6bddda9 Mon Sep 17 00:00:00 2001 From: Laurent Bercot Date: Sun, 3 Aug 2025 23:14:12 +0000 Subject: Add mkntemp, atomic_symlink4 Signed-off-by: Laurent Bercot --- doc/libunixonacid/unix-transactional.html | 17 ++++++++++++ package/deps.mak | 6 +++-- src/include/skalibs/posixplz.h | 1 + src/include/skalibs/unix-transactional.h | 4 ++- src/libposixplz/mkntemp.c | 19 ++++++++++++++ src/libunixonacid/atomic_symlink.c | 34 ++---------------------- src/libunixonacid/atomic_symlink4.c | 43 +++++++++++++++++++++++++++++++ 7 files changed, 89 insertions(+), 35 deletions(-) create mode 100644 src/libposixplz/mkntemp.c create mode 100644 src/libunixonacid/atomic_symlink4.c diff --git a/doc/libunixonacid/unix-transactional.html b/doc/libunixonacid/unix-transactional.html index 9a36173..b429001 100644 --- a/doc/libunixonacid/unix-transactional.html +++ b/doc/libunixonacid/unix-transactional.html @@ -128,5 +128,22 @@ The difference between these two functions is the same as that between rm_rf and rm_rf_tmp in djbunix.

+

Atomic symbolic link creation

+ +

+ int atomic_symlink4 (char const *target, char const *name, char *buf, size_t len) +Atomically makes a symlink named name pointing to target. If +name designated an existing file, it is unlinked. Does not work if +name is an existing directory (but will work if it is a +symlink to a directory!) Returns 1 on success, and 0 (and sets errno) on +error.
+In addition, if buf is not NULL, and points +to a buffer of nonzero length len, then if name exists prior to the +call, it must be a symbolic link, and its target be shorter than len bytes. +If these conditions are fulfilled, the operation succeeds, and buf then +contains the previous target of name, with a terminating NULL. If they are not, +the function fails with 0 (errno is ENAMETOOLONG if the buffer is too small). +

+ diff --git a/package/deps.mak b/package/deps.mak index f6481ae..b4fe193 100644 --- a/package/deps.mak +++ b/package/deps.mak @@ -54,7 +54,7 @@ src/include/skalibs/tai.h: src/include/skalibs/gccattributes.h src/include/skali src/include/skalibs/textclient.h: src/include/skalibs/allreadwrite.h src/include/skalibs/tai.h src/include/skalibs/textmessage.h src/include/skalibs/textmessage.h: src/include/skalibs/allreadwrite.h src/include/skalibs/bufalloc.h src/include/skalibs/buffer.h src/include/skalibs/gccattributes.h src/include/skalibs/stralloc.h src/include/skalibs/tai.h src/include/skalibs/unix-timed.h: src/include/skalibs/bufalloc.h src/include/skalibs/buffer.h src/include/skalibs/functypes.h src/include/skalibs/stralloc.h src/include/skalibs/tai.h -src/include/skalibs/unix-transactional.h: src/include/skalibs/direntry.h src/include/skalibs/stralloc.h +src/include/skalibs/unix-transactional.h: src/include/skalibs/direntry.h src/include/skalibs/gccattributes.h src/include/skalibs/stralloc.h src/include/skalibs/unixconnection.h: src/include/skalibs/unixmessage.h src/include/skalibs/unixmessage.h: src/include/skalibs/buffer.h src/include/skalibs/cbuffer.h src/include/skalibs/gccattributes.h src/include/skalibs/genalloc.h src/include/skalibs/stralloc.h src/include/skalibs/tai.h src/include/skalibs/unixonacid.h: src/include/skalibs/ancil.h src/include/skalibs/kolbak.h src/include/skalibs/skaclient.h src/include/skalibs/textclient.h src/include/skalibs/textmessage.h src/include/skalibs/unix-timed.h src/include/skalibs/unix-transactional.h src/include/skalibs/unixconnection.h src/include/skalibs/unixmessage.h @@ -185,6 +185,7 @@ src/libposixplz/mkfiletemp.o src/libposixplz/mkfiletemp.lo: src/libposixplz/mkfi src/libposixplz/mkhtemp.o src/libposixplz/mkhtemp.lo: src/libposixplz/mkhtemp.c src/include/skalibs/posixplz.h src/libposixplz/mklinktemp.o src/libposixplz/mklinktemp.lo: src/libposixplz/mklinktemp.c src/include/skalibs/djbunix.h src/libposixplz/posixplz-internal.h src/include/skalibs/posixplz.h src/libposixplz/mkltemp.o src/libposixplz/mkltemp.lo: src/libposixplz/mkltemp.c src/include/skalibs/posixplz.h +src/libposixplz/mkntemp.o src/libposixplz/mkntemp.lo: src/libposixplz/mkntemp.c src/include/skalibs/posixplz.h src/libposixplz/mkptemp.o src/libposixplz/mkptemp.lo: src/libposixplz/mkptemp.c src/include/skalibs/posixplz.h src/libposixplz/mkptemp2.o src/libposixplz/mkptemp2.lo: src/libposixplz/mkptemp2.c src/include/skalibs/posixplz.h src/libposixplz/mkptemp3.o src/libposixplz/mkptemp3.lo: src/libposixplz/mkptemp3.c src/include/skalibs/djbunix.h src/include/skalibs/fcntl.h src/include/skalibs/posixplz.h @@ -745,7 +746,8 @@ src/libunixonacid/ancil_recv_fd.o src/libunixonacid/ancil_recv_fd.lo: src/libuni src/libunixonacid/ancil_send_fd.o src/libunixonacid/ancil_send_fd.lo: src/libunixonacid/ancil_send_fd.c src/include/skalibs/ancil.h src/include/skalibs/nonposix.h src/include/skalibs/posixishard.h src/libunixonacid/atomic_rm_rf.o src/libunixonacid/atomic_rm_rf.lo: src/libunixonacid/atomic_rm_rf.c src/include/skalibs/skamisc.h src/include/skalibs/unix-transactional.h src/libunixonacid/atomic_rm_rf_tmp.o src/libunixonacid/atomic_rm_rf_tmp.lo: src/libunixonacid/atomic_rm_rf_tmp.c src/include/skalibs/djbunix.h src/include/skalibs/random.h src/include/skalibs/stralloc.h src/include/skalibs/unix-transactional.h -src/libunixonacid/atomic_symlink.o src/libunixonacid/atomic_symlink.lo: src/libunixonacid/atomic_symlink.c src/include/skalibs/posixplz.h src/include/skalibs/unix-transactional.h +src/libunixonacid/atomic_symlink.o src/libunixonacid/atomic_symlink.lo: src/libunixonacid/atomic_symlink.c src/include/skalibs/unix-transactional.h +src/libunixonacid/atomic_symlink4.o src/libunixonacid/atomic_symlink4.lo: src/libunixonacid/atomic_symlink4.c src/include/skalibs/posixplz.h src/include/skalibs/unix-transactional.h src/libunixonacid/bufalloc_timed_flush.o src/libunixonacid/bufalloc_timed_flush.lo: src/libunixonacid/bufalloc_timed_flush.c src/include/skalibs/bufalloc.h src/include/skalibs/functypes.h src/include/skalibs/unix-timed.h src/libunixonacid/buffer_timed_fill.o src/libunixonacid/buffer_timed_fill.lo: src/libunixonacid/buffer_timed_fill.c src/include/skalibs/allreadwrite.h src/include/skalibs/buffer.h src/include/skalibs/functypes.h src/include/skalibs/unix-timed.h src/libunixonacid/buffer_timed_flush.o src/libunixonacid/buffer_timed_flush.lo: src/libunixonacid/buffer_timed_flush.c src/include/skalibs/buffer.h src/include/skalibs/functypes.h src/include/skalibs/unix-timed.h diff --git a/src/include/skalibs/posixplz.h b/src/include/skalibs/posixplz.h index 558ccae..3c6c520 100644 --- a/src/include/skalibs/posixplz.h +++ b/src/include/skalibs/posixplz.h @@ -45,6 +45,7 @@ extern int mkdirp (char const *, mode_t) ; extern int mkdirp2 (char *, mode_t) ; extern int mkfiletemp (char *, create_func_ref, mode_t, void *) ; extern int mklinktemp (char const *, char *, link_func_ref) ; +extern int mkntemp (char *) ; extern int mkptemp (char *) ; extern int mkptemp2 (char *, unsigned int) ; extern int mkptemp3 (char *, mode_t, unsigned int) ; diff --git a/src/include/skalibs/unix-transactional.h b/src/include/skalibs/unix-transactional.h index 73a8d7f..9b884f9 100644 --- a/src/include/skalibs/unix-transactional.h +++ b/src/include/skalibs/unix-transactional.h @@ -7,6 +7,7 @@ #include #include +#include #include #include @@ -47,6 +48,7 @@ extern size_t openwritevnclose_at (int, char const *, struct iovec const *, unsi extern int atomic_rm_rf (char const *) ; extern int atomic_rm_rf_tmp (char const *, stralloc *) ; -extern int atomic_symlink (char const *, char const *, char const *) ; +extern int atomic_symlink (char const *, char const *, char const *) gccattr_deprecated ; +extern int atomic_symlink4 (char const *, char const *, char *, size_t) ; #endif diff --git a/src/libposixplz/mkntemp.c b/src/libposixplz/mkntemp.c new file mode 100644 index 0000000..42d542b --- /dev/null +++ b/src/libposixplz/mkntemp.c @@ -0,0 +1,19 @@ +/* ISC license. */ + +#include +#include + +#include + +static int f (char const *fn, mode_t mode, void *data) +{ + (void)mode ; + (void)data ; + return access(fn, F_OK) == 0 ? (errno = EEXIST, -1) : + errno == ENOENT ? (errno = 0, 0) : -1 ; +} + +int mkntemp (char *s) +{ + return mkfiletemp(s, &f, 0, 0) ; +} diff --git a/src/libunixonacid/atomic_symlink.c b/src/libunixonacid/atomic_symlink.c index a4c7ecf..13e82e6 100644 --- a/src/libunixonacid/atomic_symlink.c +++ b/src/libunixonacid/atomic_symlink.c @@ -1,39 +1,9 @@ /* ISC license. */ -#include -#include -#include -#include - -#include #include int atomic_symlink (char const *target, char const *name, char const *suffix) { - { - int e = errno ; - if (symlink(target, name) == 0) return 1 ; - if (errno != EEXIST) return 0 ; - errno = e ; - } - { - size_t namelen = strlen(name) ; - size_t suffixlen = suffix ? strlen(suffix) + 1 : 0 ; - char tmp[namelen + suffixlen + 8] ; - memcpy(tmp, name, namelen) ; - if (suffix) - { - tmp[namelen] = ':' ; - memcpy(tmp + namelen + 1, suffix, suffixlen - 1) ; - } - memcpy(tmp + namelen + suffixlen, ":XXXXXX", 7) ; - tmp[namelen + suffixlen + 7] = 0 ; - if (mkltemp(target, tmp) == -1) return 0 ; - if (rename(tmp, name) < 0) - { - unlink_void(tmp) ; - return 0 ; - } - } - return 1 ; + (void)suffix ; + return atomic_symlink4(target, name, 0, 0) ; } diff --git a/src/libunixonacid/atomic_symlink4.c b/src/libunixonacid/atomic_symlink4.c new file mode 100644 index 0000000..7b18a5e --- /dev/null +++ b/src/libunixonacid/atomic_symlink4.c @@ -0,0 +1,43 @@ +/* ISC license. */ + +#include +#include +#include +#include + +#include +#include + +int atomic_symlink4 (char const *target, char const *name, char *oldbuf, size_t oldlen) +{ + { + int e = errno ; + if (symlink(target, name) == 0) + { + if (oldbuf && oldlen) *oldbuf = 0 ; + return 1 ; + } + if (errno != EEXIST) return 0 ; + errno = e ; + } + { + size_t namelen = strlen(name) ; + char tmp[namelen + 32] ; + if (oldbuf && oldlen) + { + ssize_t r = readlink(name, oldbuf, oldlen) ; + if (r == -1) return 0 ; + if (r >= oldlen) return (errno = ENAMETOOLONG, 0) ; + oldbuf[r] = 0 ; + } + memcpy(tmp, name, namelen) ; + memcpy(tmp + namelen, ":skalibs-atomic_symlink4:XXXXXX", 32) ; + if (mkltemp(target, tmp) == -1) return 0 ; + if (rename(tmp, name) == -1) + { + unlink_void(tmp) ; + return 0 ; + } + } + return 1 ; +} -- cgit v1.3.1