Files
git/compat/mingw-posix.h
Patrick Steinhardt 3262a53c12 reftable: ignore file-in-use errors when unlink(3p) fails on Windows
Unlinking a file may fail on Windows systems when the file is still held
open by another process. This is incompatible with POSIX semantics and
by extension with Git's assumed semantics when unlinking files, which
is that files can be unlinked regardless of whether they are still open
or not. To counteract this incompatibility, we have some custom error
handling in the `mingw_unlink()` wrapper that first retries the deletion
with some delay, and then asks the user whether we should continue to
retry.

While this logic might be sensible in many callsites throughout Git, it
is less when used in the reftable library. We only use unlink(3) there
to delete tables which aren't referenced anymore, and the code is very
aware of the limitations on Windows. As such, all calls to unlink(3p)
don't perform any error checking at all and are fine with the call
failing.

Instead, the library provides the `reftable_stack_clean()` function,
which Git knows to execute in git-pack-refs(1) after compacting a stack.
The effect of this function is that all stale tables will eventually get
deleted once they aren't kept open anymore.

So while we're fine with unlink(3p) failing, the Windows-emulation of
that function will still perform several sleeps and ultimately end up
asking the user:

    $ git pack-refs
    Unlink of file 'C:/temp/jgittest/jgit/.git/reftable/0x000000000002-0x000000000004-50486d0e.ref' failed. Should I try again? (y/n) n
    Unlink of file 'C:/temp/jgittest/jgit/.git/reftable/0x000000000002-0x000000000004-50486d0e.ref' failed. Should I try again? (y/n) n
    Unlink of file 'C:/temp/jgittest/jgit/.git/reftable/0x000000000002-0x000000000004-50486d0e.ref' failed. Should I try again? (y/n) n

It even asks multiple times, which is doubly annoying and puzzling to
the user:

  1. It asks when trying to delete the old file after having written the
     compacted stack.

  2. It asks when reloading the stack, where it will try to unlink
     now-unreferenced tables.

  3. It asks when calling `reftable_stack_clean()`, where it will try to
     unlink now-stale tables.

Fix the issue by making it possible to disable this behaviour with a
preprocessor define. As "git-compat-util.h" is only included from
"system.h", and given that "system.h" is only ever included by headers
and code that are internal to the reftable library, we can set that
macro in this header without impacting anything else but the reftable
library.

Reported-by: Christian Reich <Zottelbart@t-online.de>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2025-02-18 14:29:18 -08:00

436 lines
11 KiB
C

#ifndef COMPAT_MINGW_POSIX_H
#define COMPAT_MINGW_POSIX_H
#ifdef __MINGW64_VERSION_MAJOR
#include <stdint.h>
#include <wchar.h>
typedef _sigset_t sigset_t;
#endif
#include <winsock2.h>
#include <ws2tcpip.h>
/* MinGW-w64 reports to have flockfile, but it does not actually have it. */
#ifdef __MINGW64_VERSION_MAJOR
#undef _POSIX_THREAD_SAFE_FUNCTIONS
#endif
/*
* things that are not available in header files
*/
typedef int uid_t;
typedef int socklen_t;
#ifndef __MINGW64_VERSION_MAJOR
typedef int pid_t;
#define hstrerror strerror
#endif
#define S_IFLNK 0120000 /* Symbolic link */
#define S_ISLNK(x) (((x) & S_IFMT) == S_IFLNK)
#define S_ISSOCK(x) 0
#ifndef S_IRWXG
#define S_IRGRP 0
#define S_IWGRP 0
#define S_IXGRP 0
#define S_IRWXG (S_IRGRP | S_IWGRP | S_IXGRP)
#endif
#ifndef S_IRWXO
#define S_IROTH 0
#define S_IWOTH 0
#define S_IXOTH 0
#define S_IRWXO (S_IROTH | S_IWOTH | S_IXOTH)
#endif
#define S_ISUID 0004000
#define S_ISGID 0002000
#define S_ISVTX 0001000
#define WIFEXITED(x) 1
#define WIFSIGNALED(x) 0
#define WEXITSTATUS(x) ((x) & 0xff)
#define WTERMSIG(x) SIGTERM
#ifndef EWOULDBLOCK
#define EWOULDBLOCK EAGAIN
#endif
#ifndef ELOOP
#define ELOOP EMLINK
#endif
#define SHUT_WR SD_SEND
#define SIGHUP 1
#define SIGQUIT 3
#define SIGKILL 9
#define SIGPIPE 13
#define SIGALRM 14
#define SIGCHLD 17
#define F_GETFD 1
#define F_SETFD 2
#define FD_CLOEXEC 0x1
#if !defined O_CLOEXEC && defined O_NOINHERIT
#define O_CLOEXEC O_NOINHERIT
#endif
#ifndef EAFNOSUPPORT
#define EAFNOSUPPORT WSAEAFNOSUPPORT
#endif
#ifndef ECONNABORTED
#define ECONNABORTED WSAECONNABORTED
#endif
#ifndef ENOTSOCK
#define ENOTSOCK WSAENOTSOCK
#endif
struct passwd {
char *pw_name;
char *pw_gecos;
char *pw_dir;
};
typedef void (__cdecl *sig_handler_t)(int);
struct sigaction {
sig_handler_t sa_handler;
unsigned sa_flags;
};
#define SA_RESTART 0
struct itimerval {
struct timeval it_value, it_interval;
};
#define ITIMER_REAL 0
struct utsname {
char sysname[16];
char nodename[1];
char release[16];
char version[16];
char machine[1];
};
/*
* sanitize preprocessor namespace polluted by Windows headers defining
* macros which collide with git local versions
*/
#undef HELP_COMMAND /* from winuser.h */
/*
* trivial stubs
*/
static inline int readlink(const char *path UNUSED, char *buf UNUSED, size_t bufsiz UNUSED)
{ errno = ENOSYS; return -1; }
static inline int symlink(const char *oldpath UNUSED, const char *newpath UNUSED)
{ errno = ENOSYS; return -1; }
static inline int fchmod(int fildes UNUSED, mode_t mode UNUSED)
{ errno = ENOSYS; return -1; }
#ifndef __MINGW64_VERSION_MAJOR
static inline pid_t fork(void)
{ errno = ENOSYS; return -1; }
#endif
static inline unsigned int alarm(unsigned int seconds UNUSED)
{ return 0; }
static inline int fsync(int fd)
{ return _commit(fd); }
static inline void sync(void)
{}
static inline uid_t getuid(void)
{ return 1; }
static inline struct passwd *getpwnam(const char *name UNUSED)
{ return NULL; }
static inline int fcntl(int fd UNUSED, int cmd, ...)
{
if (cmd == F_GETFD || cmd == F_SETFD)
return 0;
errno = EINVAL;
return -1;
}
#define sigemptyset(x) (void)0
static inline int sigaddset(sigset_t *set UNUSED, int signum UNUSED)
{ return 0; }
#define SIG_BLOCK 0
#define SIG_UNBLOCK 0
static inline int sigprocmask(int how UNUSED, const sigset_t *set UNUSED, sigset_t *oldset UNUSED)
{ return 0; }
static inline pid_t getppid(void)
{ return 1; }
static inline pid_t getpgid(pid_t pid)
{ return pid == 0 ? getpid() : pid; }
static inline pid_t tcgetpgrp(int fd UNUSED)
{ return getpid(); }
/*
* simple adaptors
*/
int mingw_mkdir(const char *path, int mode);
#define mkdir mingw_mkdir
#define WNOHANG 1
pid_t waitpid(pid_t pid, int *status, int options);
#define kill mingw_kill
int mingw_kill(pid_t pid, int sig);
#define locate_in_PATH mingw_locate_in_PATH
char *mingw_locate_in_PATH(const char *cmd);
/*
* implementations of missing functions
*/
int pipe(int filedes[2]);
unsigned int sleep (unsigned int seconds);
int mkstemp(char *template);
int gettimeofday(struct timeval *tv, void *tz);
#ifndef __MINGW64_VERSION_MAJOR
struct tm *gmtime_r(const time_t *timep, struct tm *result);
struct tm *localtime_r(const time_t *timep, struct tm *result);
#endif
int getpagesize(void); /* defined in MinGW's libgcc.a */
struct passwd *getpwuid(uid_t uid);
int setitimer(int type, struct itimerval *in, struct itimerval *out);
int sigaction(int sig, struct sigaction *in, struct sigaction *out);
int link(const char *oldpath, const char *newpath);
int uname(struct utsname *buf);
/*
* replacements of existing functions
*/
int mingw_unlink(const char *pathname, int handle_in_use_error);
#ifdef MINGW_DONT_HANDLE_IN_USE_ERROR
# define unlink(path) mingw_unlink(path, 0)
#else
# define unlink(path) mingw_unlink(path, 1)
#endif
int mingw_rmdir(const char *path);
#define rmdir mingw_rmdir
int mingw_open (const char *filename, int oflags, ...);
#define open mingw_open
#undef OPEN_RETURNS_EINTR
int mingw_fgetc(FILE *stream);
#define fgetc mingw_fgetc
FILE *mingw_fopen (const char *filename, const char *otype);
#define fopen mingw_fopen
FILE *mingw_freopen (const char *filename, const char *otype, FILE *stream);
#define freopen mingw_freopen
int mingw_fflush(FILE *stream);
#define fflush mingw_fflush
ssize_t mingw_write(int fd, const void *buf, size_t len);
#define write mingw_write
int mingw_access(const char *filename, int mode);
#undef access
#define access mingw_access
int mingw_chdir(const char *dirname);
#define chdir mingw_chdir
int mingw_chmod(const char *filename, int mode);
#define chmod mingw_chmod
char *mingw_mktemp(char *template);
#define mktemp mingw_mktemp
char *mingw_getcwd(char *pointer, int len);
#define getcwd mingw_getcwd
#ifdef NO_UNSETENV
#error "NO_UNSETENV is incompatible with the Windows-specific startup code!"
#endif
/*
* We bind *env() routines (even the mingw_ ones) to private mingw_ versions.
* These talk to the CRT using UNICODE/wchar_t, but maintain the original
* narrow-char API.
*
* Note that the MSCRT maintains both ANSI (getenv()) and UNICODE (_wgetenv())
* routines and stores both versions of each environment variable in parallel
* (and secretly updates both when you set one or the other), but it uses CP_ACP
* to do the conversion rather than CP_UTF8.
*
* Since everything in the git code base is UTF8, we define the mingw_ routines
* to access the CRT using the UNICODE routines and manually convert them to
* UTF8. This also avoids round-trip problems.
*
* This also helps with our linkage, since "_wenviron" is publicly exported
* from the CRT. But to access "_environ" we would have to statically link
* to the CRT (/MT).
*
* We require NO_SETENV (and let gitsetenv() call our mingw_putenv).
*/
#define getenv mingw_getenv
#define putenv mingw_putenv
#define unsetenv mingw_putenv
char *mingw_getenv(const char *name);
int mingw_putenv(const char *name);
int mingw_gethostname(char *host, int namelen);
#define gethostname mingw_gethostname
struct hostent *mingw_gethostbyname(const char *host);
#define gethostbyname mingw_gethostbyname
int mingw_getaddrinfo(const char *node, const char *service,
const struct addrinfo *hints, struct addrinfo **res);
#define getaddrinfo mingw_getaddrinfo
int mingw_socket(int domain, int type, int protocol);
#define socket mingw_socket
int mingw_connect(int sockfd, struct sockaddr *sa, size_t sz);
#define connect mingw_connect
int mingw_bind(int sockfd, struct sockaddr *sa, size_t sz);
#define bind mingw_bind
int mingw_setsockopt(int sockfd, int lvl, int optname, void *optval, int optlen);
#define setsockopt mingw_setsockopt
int mingw_shutdown(int sockfd, int how);
#define shutdown mingw_shutdown
int mingw_listen(int sockfd, int backlog);
#define listen mingw_listen
int mingw_accept(int sockfd, struct sockaddr *sa, socklen_t *sz);
#define accept mingw_accept
int mingw_rename(const char*, const char*);
#define rename mingw_rename
#if defined(USE_WIN32_MMAP) || defined(_MSC_VER)
int mingw_getpagesize(void);
#define getpagesize mingw_getpagesize
#endif
int win32_fsync_no_flush(int fd);
#define fsync_no_flush win32_fsync_no_flush
#define FSYNC_COMPONENTS_PLATFORM_DEFAULT (FSYNC_COMPONENTS_DEFAULT | FSYNC_COMPONENT_LOOSE_OBJECT)
#define FSYNC_METHOD_DEFAULT (FSYNC_METHOD_BATCH)
struct rlimit {
unsigned int rlim_cur;
};
#define RLIMIT_NOFILE 0
static inline int getrlimit(int resource, struct rlimit *rlp)
{
if (resource != RLIMIT_NOFILE) {
errno = EINVAL;
return -1;
}
rlp->rlim_cur = 2048;
return 0;
}
/*
* Use mingw specific stat()/lstat()/fstat() implementations on Windows,
* including our own struct stat with 64 bit st_size and nanosecond-precision
* file times.
*/
#ifndef __MINGW64_VERSION_MAJOR
#define off_t off64_t
#define lseek _lseeki64
#ifndef _MSC_VER
struct timespec {
time_t tv_sec;
long tv_nsec;
};
#endif
#endif
struct mingw_stat {
_dev_t st_dev;
_ino_t st_ino;
_mode_t st_mode;
short st_nlink;
short st_uid;
short st_gid;
_dev_t st_rdev;
off64_t st_size;
struct timespec st_atim;
struct timespec st_mtim;
struct timespec st_ctim;
};
#define st_atime st_atim.tv_sec
#define st_mtime st_mtim.tv_sec
#define st_ctime st_ctim.tv_sec
#ifdef stat
#undef stat
#endif
#define stat mingw_stat
int mingw_lstat(const char *file_name, struct stat *buf);
int mingw_stat(const char *file_name, struct stat *buf);
int mingw_fstat(int fd, struct stat *buf);
#ifdef fstat
#undef fstat
#endif
#define fstat mingw_fstat
#ifdef lstat
#undef lstat
#endif
#define lstat mingw_lstat
int mingw_utime(const char *file_name, const struct utimbuf *times);
#define utime mingw_utime
size_t mingw_strftime(char *s, size_t max,
const char *format, const struct tm *tm);
#define strftime mingw_strftime
pid_t mingw_spawnvpe(const char *cmd, const char **argv, char **env,
const char *dir,
int fhin, int fhout, int fherr);
int mingw_execvp(const char *cmd, char *const *argv);
#define execvp mingw_execvp
int mingw_execv(const char *cmd, char *const *argv);
#define execv mingw_execv
static inline unsigned int git_ntohl(unsigned int x)
{ return (unsigned int)ntohl(x); }
#define ntohl git_ntohl
sig_handler_t mingw_signal(int sig, sig_handler_t handler);
#define signal mingw_signal
int mingw_raise(int sig);
#define raise mingw_raise
/*
* ANSI emulation wrappers
*/
int winansi_isatty(int fd);
#define isatty winansi_isatty
int winansi_dup2(int oldfd, int newfd);
#define dup2 winansi_dup2
void winansi_init(void);
HANDLE winansi_get_osfhandle(int fd);
#if !defined(__MINGW64_VERSION_MAJOR) && (!defined(_MSC_VER) || _MSC_VER < 1800)
#define PRIuMAX "I64u"
#define PRId64 "I64d"
#else
#include <inttypes.h>
#endif
#endif /* COMPAT_MINGW_POSIX_H */