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-rw-r--r--text.c297
1 files changed, 184 insertions, 113 deletions
diff --git a/text.c b/text.c
index 8bdb5e5..9358c9a 100644
--- a/text.c
+++ b/text.c
@@ -36,7 +36,11 @@ struct Buffer {
size_t size; /* maximal capacity */
size_t len; /* current used length / insertion position */
char *data; /* actual data */
- enum { MMAP, MALLOC} type; /* type of allocation */
+ enum { /* type of allocation */
+ MMAP_ORIG, /* mmap(2)-ed from an external file */
+ MMAP, /* mmap(2)-ed from a temporary file only known to this process */
+ MALLOC, /* heap allocated buffer using malloc(3) */
+ } type;
Buffer *next; /* next junk */
};
@@ -118,6 +122,18 @@ struct Text {
enum TextNewLine newlines; /* which type of new lines does the file use */
};
+struct TextSave { /* used to hold context between text_save_{begin,commit} calls */
+ Text *txt; /* text to operate on */
+ char *filename; /* filename to save to as given to text_save_begin */
+ char *tmpname; /* temporary name used for atomic rename(2) */
+ int fd; /* file descriptor to write data to using text_save_write */
+ enum {
+ TEXT_SAVE_UNKNOWN,
+ TEXT_SAVE_ATOMIC, /* create a new file, write content, atomically rename(2) over old file */
+ TEXT_SAVE_INPLACE, /* truncate file, overwrite content (any error will result in data loss) */
+ } type;
+};
+
/* buffer management */
static Buffer *buffer_alloc(Text *txt, size_t size);
static Buffer *buffer_read(Text *txt, size_t size, int fd);
@@ -220,7 +236,7 @@ static Buffer *buffer_mmap(Text *txt, size_t size, int fd, off_t offset) {
return NULL;
}
}
- buf->type = MMAP;
+ buf->type = MMAP_ORIG;
buf->size = size;
buf->len = size;
buf->next = txt->buffers;
@@ -233,7 +249,7 @@ static void buffer_free(Buffer *buf) {
return;
if (buf->type == MALLOC)
free(buf->data);
- else if (buf->type == MMAP && buf->data)
+ else if ((buf->type == MMAP_ORIG || buf->type == MMAP) && buf->data)
munmap(buf->data, buf->size);
free(buf);
}
@@ -807,9 +823,12 @@ static bool preserve_selinux_context(int src, int dest) {
return true;
}
-/* Save current content to given filename. The data is first saved to `filename~`
- * and then atomically moved to its final (possibly alredy existing) destination
- * using rename(2). This approach does not work if:
+/* Create a new file named `filename~` and try to preserve all important
+ * meta data. After the file content has been written to this temporary
+ * file, text_save_commit_atomic will atomically move it to its final
+ * (possibly already existing) destination using rename(2).
+ *
+ * This approach does not work if:
*
* - the file is a symbolic link
* - the file is a hard link
@@ -819,16 +838,12 @@ static bool preserve_selinux_context(int src, int dest) {
* - POSXI ACL can not be preserved (if enabled)
* - SELinux security context can not be preserved (if enabled)
*/
-static bool text_save_atomic_range(Text *txt, Filerange *range, const char *filename) {
- struct stat meta = { 0 }, oldmeta = { 0 };
- int fd = -1, oldfd = -1, saved_errno;
- char *tmpname = NULL;
- size_t size = text_range_size(range);
- size_t namelen = strlen(filename) + 1 /* ~ */ + 1 /* \0 */;
-
- if ((oldfd = open(filename, O_RDONLY)) == -1 && errno != ENOENT)
+static bool text_save_begin_atomic(TextSave *ctx) {
+ int oldfd, saved_errno;
+ if ((oldfd = open(ctx->filename, O_RDONLY)) == -1 && errno != ENOENT)
goto err;
- if (oldfd != -1 && lstat(filename, &oldmeta) == -1)
+ struct stat oldmeta = { 0 };
+ if (oldfd != -1 && lstat(ctx->filename, &oldmeta) == -1)
goto err;
if (oldfd != -1) {
if (S_ISLNK(oldmeta.st_mode)) /* symbolic link */
@@ -836,110 +851,71 @@ static bool text_save_atomic_range(Text *txt, Filerange *range, const char *file
if (oldmeta.st_nlink > 1) /* hard link */
goto err;
}
- if (!(tmpname = calloc(1, namelen)))
- goto err;
- snprintf(tmpname, namelen, "%s~", filename);
- /* O_RDWR is needed because otherwise we can't map with MAP_SHARED */
- if ((fd = open(tmpname, O_CREAT|O_RDWR|O_TRUNC, oldfd == -1 ? S_IRUSR|S_IWUSR : oldmeta.st_mode)) == -1)
+ size_t namelen = strlen(ctx->filename) + 1 /* ~ */ + 1 /* \0 */;
+ if (!(ctx->tmpname = calloc(1, namelen)))
goto err;
- if (ftruncate(fd, size) == -1)
+ snprintf(ctx->tmpname, namelen, "%s~", ctx->filename);
+
+ if ((ctx->fd = open(ctx->tmpname, O_CREAT|O_WRONLY|O_TRUNC, oldfd == -1 ? S_IRUSR|S_IWUSR : oldmeta.st_mode)) == -1)
goto err;
if (oldfd != -1) {
- if (!preserve_acl(oldfd, fd) || !preserve_selinux_context(oldfd, fd))
+ if (!preserve_acl(oldfd, ctx->fd) || !preserve_selinux_context(oldfd, ctx->fd))
goto err;
/* change owner if necessary */
- if (oldmeta.st_uid != getuid() && fchown(fd, oldmeta.st_uid, (uid_t)-1) == -1)
+ if (oldmeta.st_uid != getuid() && fchown(ctx->fd, oldmeta.st_uid, (uid_t)-1) == -1)
goto err;
/* change group if necessary, in case of failure some editors reset
* the group permissions to the same as for others */
- if (oldmeta.st_gid != getgid() && fchown(fd, (uid_t)-1, oldmeta.st_gid) == -1)
- goto err;
- }
-
- if (size > 0) {
- void *buf = mmap(NULL, size, PROT_WRITE, MAP_SHARED, fd, 0);
- if (buf == MAP_FAILED)
+ if (oldmeta.st_gid != getgid() && fchown(ctx->fd, (uid_t)-1, oldmeta.st_gid) == -1)
goto err;
-
- char *cur = buf;
- size_t rem = size;
-
- for (Iterator it = text_iterator_get(txt, range->start);
- rem > 0 && text_iterator_valid(&it);
- text_iterator_next(&it)) {
- size_t len = it.end - it.text;
- if (len > rem)
- len = rem;
- memcpy(cur, it.text, len);
- cur += len;
- rem -= len;
- }
-
- if (munmap(buf, size) == -1)
- goto err;
- }
-
- if (oldfd != -1) {
close(oldfd);
- oldfd = -1;
}
- if (fsync(fd) == -1)
- goto err;
-
- if (fstat(fd, &meta) == -1)
- goto err;
-
- if (close(fd) == -1) {
- fd = -1;
- goto err;
- }
- fd = -1;
-
- if (rename(tmpname, filename) == -1)
- goto err;
-
- if (meta.st_mtime)
- txt->info = meta;
- free(tmpname);
+ ctx->type = TEXT_SAVE_ATOMIC;
return true;
err:
saved_errno = errno;
if (oldfd != -1)
close(oldfd);
- if (fd != -1)
- close(fd);
- if (tmpname && *tmpname)
- unlink(tmpname);
- free(tmpname);
+ if (ctx->fd != -1)
+ close(ctx->fd);
+ ctx->fd = -1;
errno = saved_errno;
return false;
}
-bool text_save(Text *txt, const char *filename) {
- Filerange r = (Filerange){ .start = 0, .end = text_size(txt) };
- return text_save_range(txt, &r, filename);
+static bool text_save_commit_atomic(TextSave *ctx) {
+ if (fsync(ctx->fd) == -1)
+ return false;
+
+ struct stat meta = { 0 };
+ if (fstat(ctx->fd, &meta) == -1)
+ return false;
+
+ bool close_failed = close(ctx->fd) == -1;
+ ctx->fd = -1;
+ if (close_failed)
+ return false;
+
+ if (rename(ctx->tmpname, ctx->filename) == -1)
+ return false;
+
+ if (meta.st_mtime)
+ ctx->txt->info = meta;
+ return true;
}
-/* First try to save the file atomically using rename(2) if this does not
- * work overwrite the file in place. However if something goes wrong during
- * this overwrite the original file is permanently damaged.
- */
-bool text_save_range(Text *txt, Filerange *range, const char *filename) {
- struct stat meta;
- int fd = -1, newfd = -1;
- errno = 0;
- if (!filename || text_save_atomic_range(txt, range, filename))
- goto ok;
- if (errno == ENOSPC)
- goto err;
- if ((fd = open(filename, O_CREAT|O_WRONLY, S_IRUSR|S_IWUSR)) == -1)
+static bool text_save_begin_inplace(TextSave *ctx) {
+ Text *txt = ctx->txt;
+ struct stat meta = { 0 };
+ int newfd = -1, saved_errno;
+ if ((ctx->fd = open(ctx->filename, O_CREAT|O_WRONLY, S_IRUSR|S_IWUSR)) == -1)
goto err;
- if (fstat(fd, &meta) == -1)
+ if (fstat(ctx->fd, &meta) == -1)
goto err;
if (meta.st_dev == txt->info.st_dev && meta.st_ino == txt->info.st_ino &&
- txt->buf && txt->buf->type == MMAP && txt->buf->size) {
+ txt->buf && txt->buf->type == MMAP_ORIG && txt->buf->size) {
/* The file we are going to overwrite is currently mmap-ed from
* text_load, therefore we copy the mmap-ed buffer to a temporary
* file and remap it at the same position such that all pointers
@@ -967,40 +943,134 @@ bool text_save_range(Text *txt, Filerange *range, const char *filename) {
munmap(data, size);
goto err;
}
- if (close(newfd) == -1) {
- newfd = -1;
+ bool close_failed = (close(newfd) == -1);
+ newfd = -1;
+ if (close_failed)
goto err;
- }
txt->buf->data = data;
+ txt->buf->type = MMAP;
newfd = -1;
}
/* overwrite the exisiting file content, if somehting goes wrong
* here we are screwed, TODO: make a backup before? */
- if (ftruncate(fd, 0) == -1)
- goto err;
- ssize_t written = text_write_range(txt, range, fd);
- if (written == -1 || (size_t)written != text_range_size(range))
- goto err;
-
- if (fsync(fd) == -1)
- goto err;
- if (fstat(fd, &meta) == -1)
+ if (ftruncate(ctx->fd, 0) == -1)
goto err;
- if (close(fd) == -1)
- return false;
- txt->info = meta;
-ok:
- txt->saved_action = txt->history;
- text_snapshot(txt);
+ ctx->type = TEXT_SAVE_INPLACE;
return true;
err:
- if (fd != -1)
- close(fd);
+ saved_errno = errno;
if (newfd != -1)
close(newfd);
+ if (ctx->fd != -1)
+ close(ctx->fd);
+ ctx->fd = -1;
+ errno = saved_errno;
return false;
}
+static bool text_save_commit_inplace(TextSave *ctx) {
+ if (fsync(ctx->fd) == -1)
+ return false;
+ struct stat meta = { 0 };
+ if (fstat(ctx->fd, &meta) == -1)
+ return false;
+ if (close(ctx->fd) == -1)
+ return false;
+ ctx->txt->info = meta;
+ return true;
+}
+
+TextSave *text_save_begin(Text *txt, const char *filename) {
+ if (!filename)
+ return NULL;
+ TextSave *ctx = calloc(1, sizeof *ctx);
+ if (!ctx)
+ return NULL;
+ ctx->txt = txt;
+ ctx->fd = -1;
+ if (!(ctx->filename = strdup(filename)))
+ goto err;
+ errno = 0;
+ if (text_save_begin_atomic(ctx))
+ return ctx;
+ if (errno == ENOSPC)
+ goto err;
+ if (text_save_begin_inplace(ctx))
+ return ctx;
+err:
+ text_save_cancel(ctx);
+ return NULL;
+}
+
+bool text_save_commit(TextSave *ctx) {
+ if (!ctx)
+ return true;
+ bool ret;
+ Text *txt = ctx->txt;
+ switch (ctx->type) {
+ case TEXT_SAVE_ATOMIC:
+ ret = text_save_commit_atomic(ctx);
+ break;
+ case TEXT_SAVE_INPLACE:
+ ret = text_save_commit_inplace(ctx);
+ break;
+ default:
+ ret = false;
+ break;
+ }
+
+ if (ret) {
+ txt->saved_action = txt->history;
+ text_snapshot(txt);
+ }
+ text_save_cancel(ctx);
+ return ret;
+}
+
+void text_save_cancel(TextSave *ctx) {
+ if (!ctx)
+ return;
+ int saved_errno = errno;
+ if (ctx->fd != -1)
+ close(ctx->fd);
+ if (ctx->tmpname && ctx->tmpname[0])
+ unlink(ctx->tmpname);
+ free(ctx->tmpname);
+ free(ctx->filename);
+ free(ctx);
+ errno = saved_errno;
+}
+
+bool text_save(Text *txt, const char *filename) {
+ Filerange r = (Filerange){ .start = 0, .end = text_size(txt) };
+ return text_save_range(txt, &r, filename);
+}
+
+/* First try to save the file atomically using rename(2) if this does not
+ * work overwrite the file in place. However if something goes wrong during
+ * this overwrite the original file is permanently damaged.
+ */
+bool text_save_range(Text *txt, Filerange *range, const char *filename) {
+ if (!filename) {
+ txt->saved_action = txt->history;
+ text_snapshot(txt);
+ return true;
+ }
+ TextSave *ctx = text_save_begin(txt, filename);
+ if (!ctx)
+ return false;
+ ssize_t written = text_write_range(txt, range, ctx->fd);
+ if (written == -1 || (size_t)written != text_range_size(range)) {
+ text_save_cancel(ctx);
+ return false;
+ }
+ return text_save_commit(ctx);
+}
+
+ssize_t text_save_write_range(TextSave *ctx, Filerange *range) {
+ return text_write_range(ctx->txt, range, ctx->fd);
+}
+
ssize_t text_write(Text *txt, int fd) {
Filerange r = (Filerange){ .start = 0, .end = text_size(txt) };
return text_write_range(txt, &r, fd);
@@ -1223,7 +1293,8 @@ bool text_modified(Text *txt) {
bool text_sigbus(Text *txt, const char *addr) {
for (Buffer *buf = txt->buffers; buf; buf = buf->next) {
- if (buf->type == MMAP && buf->data <= addr && addr < buf->data + buf->size)
+ if ((buf->type == MMAP_ORIG || buf->type == MMAP) &&
+ buf->data <= addr && addr < buf->data + buf->size)
return true;
}
return false;
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