diff options
Diffstat (limited to 'tempfile.h')
| -rw-r--r-- | tempfile.h | 123 |
1 files changed, 56 insertions, 67 deletions
diff --git a/tempfile.h b/tempfile.h index 2f0038decd..b8f4b5e145 100644 --- a/tempfile.h +++ b/tempfile.h @@ -1,6 +1,8 @@ #ifndef TEMPFILE_H #define TEMPFILE_H +#include "list.h" + /* * Handle temporary files. * @@ -15,25 +17,18 @@ * * The caller: * - * * Allocates a `struct tempfile` either as a static variable or on - * the heap, initialized to zeros. Once you use the structure to - * call `create_tempfile()`, it belongs to the tempfile subsystem - * and its storage must remain valid throughout the life of the - * program (i.e. you cannot use an on-stack variable to hold this - * structure). - * * * Attempts to create a temporary file by calling - * `create_tempfile()`. + * `create_tempfile()`. The resources used for the temporary file are + * managed by the tempfile API. * * * Writes new content to the file by either: * - * * writing to the file descriptor returned by `create_tempfile()` - * (also available via `tempfile->fd`). + * * writing to the `tempfile->fd` file descriptor * * * calling `fdopen_tempfile()` to get a `FILE` pointer for the * open file and writing to the file using stdio. * - * Note that the file descriptor returned by create_tempfile() + * Note that the file descriptor created by create_tempfile() * is marked O_CLOEXEC, so the new contents must be written by * the current process, not any spawned one. * @@ -47,19 +42,18 @@ * control of the file. * * * Close the file descriptor without removing or renaming the - * temporary file by calling `close_tempfile()`, and later call + * temporary file by calling `close_tempfile_gently()`, and later call * `delete_tempfile()` or `rename_tempfile()`. * - * Even after the temporary file is renamed or deleted, the `tempfile` - * object must not be freed or altered by the caller. However, it may - * be reused; just pass it to another call of `create_tempfile()`. + * After the temporary file is renamed or deleted, the `tempfile` + * object is no longer valid and should not be reused. * * If the program exits before `rename_tempfile()` or * `delete_tempfile()` is called, an `atexit(3)` handler will close * and remove the temporary file. * * If you need to close the file descriptor yourself, do so by calling - * `close_tempfile()`. You should never call `close(2)` or `fclose(3)` + * `close_tempfile_gently()`. You should never call `close(2)` or `fclose(3)` * yourself, otherwise the `struct tempfile` structure would still * think that the file descriptor needs to be closed, and a later * cleanup would result in duplicate calls to `close(2)`. Worse yet, @@ -71,30 +65,30 @@ * Error handling * -------------- * - * `create_tempfile()` returns a file descriptor on success or -1 on - * failure. On errors, `errno` describes the reason for failure. + * `create_tempfile()` returns an allocated tempfile on success or NULL + * on failure. On errors, `errno` describes the reason for failure. * - * `delete_tempfile()`, `rename_tempfile()`, and `close_tempfile()` - * return 0 on success. On failure they set `errno` appropriately, do - * their best to delete the temporary file, and return -1. + * `delete_tempfile()`, `rename_tempfile()`, and `close_tempfile_gently()` + * return 0 on success. On failure they set `errno` appropriately and return + * -1. `delete` and `rename` (but not `close`) do their best to delete the + * temporary file before returning. */ struct tempfile { - struct tempfile *volatile next; + volatile struct volatile_list_head list; volatile sig_atomic_t active; volatile int fd; FILE *volatile fp; volatile pid_t owner; - char on_list; struct strbuf filename; }; /* * Attempt to create a temporary file at the specified `path`. Return - * a file descriptor for writing to it, or -1 on error. It is an error - * if a file already exists at that path. + * a tempfile (whose "fd" member can be used for writing to it), or + * NULL on error. It is an error if a file already exists at that path. */ -extern int create_tempfile(struct tempfile *tempfile, const char *path); +extern struct tempfile *create_tempfile(const char *path); /* * Register an existing file as a tempfile, meaning that it will be @@ -102,7 +96,7 @@ extern int create_tempfile(struct tempfile *tempfile, const char *path); * but it can be worked with like any other closed tempfile (for * example, it can be opened using reopen_tempfile()). */ -extern void register_tempfile(struct tempfile *tempfile, const char *path); +extern struct tempfile *register_tempfile(const char *path); /* @@ -134,83 +128,78 @@ extern void register_tempfile(struct tempfile *tempfile, const char *path); * know the (absolute) path of the file that was created, it can be * read from tempfile->filename. * - * On success, the functions return a file descriptor that is open for - * writing the temporary file. On errors, they return -1 and set errno - * appropriately (except for the "x" variants, which die() on errors). + * On success, the functions return a tempfile whose "fd" member is open + * for writing the temporary file. On errors, they return NULL and set + * errno appropriately (except for the "x" variants, which die() on + * errors). */ /* See "mks_tempfile functions" above. */ -extern int mks_tempfile_sm(struct tempfile *tempfile, - const char *template, int suffixlen, int mode); +extern struct tempfile *mks_tempfile_sm(const char *template, + int suffixlen, int mode); /* See "mks_tempfile functions" above. */ -static inline int mks_tempfile_s(struct tempfile *tempfile, - const char *template, int suffixlen) +static inline struct tempfile *mks_tempfile_s(const char *template, + int suffixlen) { - return mks_tempfile_sm(tempfile, template, suffixlen, 0600); + return mks_tempfile_sm(template, suffixlen, 0600); } /* See "mks_tempfile functions" above. */ -static inline int mks_tempfile_m(struct tempfile *tempfile, - const char *template, int mode) +static inline struct tempfile *mks_tempfile_m(const char *template, int mode) { - return mks_tempfile_sm(tempfile, template, 0, mode); + return mks_tempfile_sm(template, 0, mode); } /* See "mks_tempfile functions" above. */ -static inline int mks_tempfile(struct tempfile *tempfile, - const char *template) +static inline struct tempfile *mks_tempfile(const char *template) { - return mks_tempfile_sm(tempfile, template, 0, 0600); + return mks_tempfile_sm(template, 0, 0600); } /* See "mks_tempfile functions" above. */ -extern int mks_tempfile_tsm(struct tempfile *tempfile, - const char *template, int suffixlen, int mode); +extern struct tempfile *mks_tempfile_tsm(const char *template, + int suffixlen, int mode); /* See "mks_tempfile functions" above. */ -static inline int mks_tempfile_ts(struct tempfile *tempfile, - const char *template, int suffixlen) +static inline struct tempfile *mks_tempfile_ts(const char *template, + int suffixlen) { - return mks_tempfile_tsm(tempfile, template, suffixlen, 0600); + return mks_tempfile_tsm(template, suffixlen, 0600); } /* See "mks_tempfile functions" above. */ -static inline int mks_tempfile_tm(struct tempfile *tempfile, - const char *template, int mode) +static inline struct tempfile *mks_tempfile_tm(const char *template, int mode) { - return mks_tempfile_tsm(tempfile, template, 0, mode); + return mks_tempfile_tsm(template, 0, mode); } /* See "mks_tempfile functions" above. */ -static inline int mks_tempfile_t(struct tempfile *tempfile, - const char *template) +static inline struct tempfile *mks_tempfile_t(const char *template) { - return mks_tempfile_tsm(tempfile, template, 0, 0600); + return mks_tempfile_tsm(template, 0, 0600); } /* See "mks_tempfile functions" above. */ -extern int xmks_tempfile_m(struct tempfile *tempfile, - const char *template, int mode); +extern struct tempfile *xmks_tempfile_m(const char *template, int mode); /* See "mks_tempfile functions" above. */ -static inline int xmks_tempfile(struct tempfile *tempfile, - const char *template) +static inline struct tempfile *xmks_tempfile(const char *template) { - return xmks_tempfile_m(tempfile, template, 0600); + return xmks_tempfile_m(template, 0600); } /* * Associate a stdio stream with the temporary file (which must still * be open). Return `NULL` (*without* deleting the file) on error. The - * stream is closed automatically when `close_tempfile()` is called or + * stream is closed automatically when `close_tempfile_gently()` is called or * when the file is deleted or renamed. */ extern FILE *fdopen_tempfile(struct tempfile *tempfile, const char *mode); static inline int is_tempfile_active(struct tempfile *tempfile) { - return tempfile->active; + return tempfile && tempfile->active; } /* @@ -226,20 +215,20 @@ extern FILE *get_tempfile_fp(struct tempfile *tempfile); * If the temporary file is still open, close it (and the file pointer * too, if it has been opened using `fdopen_tempfile()`) without * deleting the file. Return 0 upon success. On failure to `close(2)`, - * return a negative value and delete the file. Usually - * `delete_tempfile()` or `rename_tempfile()` should eventually be - * called if `close_tempfile()` succeeds. + * return a negative value. Usually `delete_tempfile()` or `rename_tempfile()` + * should eventually be called regardless of whether `close_tempfile_gently()` + * succeeds. */ -extern int close_tempfile(struct tempfile *tempfile); +extern int close_tempfile_gently(struct tempfile *tempfile); /* * Re-open a temporary file that has been closed using - * `close_tempfile()` but not yet deleted or renamed. This can be used + * `close_tempfile_gently()` but not yet deleted or renamed. This can be used * to implement a sequence of operations like the following: * * * Create temporary file. * - * * Write new contents to file, then `close_tempfile()` to cause the + * * Write new contents to file, then `close_tempfile_gently()` to cause the * contents to be written to disk. * * * Pass the name of the temporary file to another program to allow @@ -259,7 +248,7 @@ extern int reopen_tempfile(struct tempfile *tempfile); * `delete_tempfile()` for a `tempfile` object that has already been * deleted or renamed. */ -extern void delete_tempfile(struct tempfile *tempfile); +extern void delete_tempfile(struct tempfile **tempfile_p); /* * Close the file descriptor and/or file pointer if they are still @@ -270,6 +259,6 @@ extern void delete_tempfile(struct tempfile *tempfile); * `rename(2)`. It is a bug to call `rename_tempfile()` for a * `tempfile` object that is not currently active. */ -extern int rename_tempfile(struct tempfile *tempfile, const char *path); +extern int rename_tempfile(struct tempfile **tempfile_p, const char *path); #endif /* TEMPFILE_H */ |