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r14831@catbus: nickm | 2007-08-29 14:17:42 -0400

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Refactor write_chunks_to_file_impl: break out the "pick a temporary name if it makes sense, and open the right filename" logic and the "close the file and unlink or rename if necessary" logic.  This will let us write big files in a smarter way than "Build a big string" or "make a list of chunks", once we get around to using it.


svn:r11300
This commit is contained in:
Nick Mathewson 2007-08-29 19:02:37 +00:00
parent 91f83cfc2d
commit 8408122222
2 changed files with 114 additions and 38 deletions
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147
src/common/util.c
View File

@ -1459,6 +1459,106 @@ write_str_to_file(const char *fname, const char *str, int bin)
return write_bytes_to_file(fname, str, strlen(str), bin);
}
/** DOCDOC */
struct open_file_t {
char *tempname;
char *filename;
int rename_on_close;
int fd;
};
/** DOCDOC */
int
start_writing_to_file(const char *fname, int open_flags, int mode,
open_file_t **data_out)
{
size_t tempname_len = strlen(fname)+16;
open_file_t *new_file = tor_malloc_zero(sizeof(open_file_t));
const char *open_name;
tor_assert(fname);
tor_assert(data_out);
new_file->fd = -1;
tempname_len = strlen(fname)+16;
tor_assert(tempname_len > strlen(fname)); /*check for overflow*/
new_file->filename = tor_strdup(fname);
if (open_flags & O_APPEND) {
open_name = fname;
new_file->rename_on_close = 0;
} else {
new_file->tempname = tor_malloc(tempname_len);
if (tor_snprintf(new_file->tempname, tempname_len, "%s.tmp", fname)<0) {
log(LOG_WARN, LD_GENERAL, "Failed to generate filename");
goto err;
}
new_file->rename_on_close = 1;
}
if ((new_file->fd = open(new_file->tempname, open_flags, mode))
< 0) {
log(LOG_WARN, LD_FS, "Couldn't open \"%s\" for writing: %s",
new_file->tempname, strerror(errno));
goto err;
}
*data_out = new_file;
return new_file->fd;
err:
*data_out = NULL;
tor_free(new_file->filename);
tor_free(new_file->tempname);
tor_free(new_file);
return -1;
}
/** DOCDOC */
static int
finish_writing_to_file_impl(open_file_t *file_data, int abort_write)
{
int r = 0;
tor_assert(file_data && file_data->filename);
if (file_data->fd >= 0 && close(file_data->fd) < 0) {
log_warn(LD_FS, "Error flushing \"%s\": %s", file_data->filename,
strerror(errno));
abort_write = 1;
r = -1;
}
if (file_data->rename_on_close) {
tor_assert(file_data->tempname && file_data->filename);
if (abort_write) {
unlink(file_data->tempname);
} else {
tor_assert(strcmp(file_data->filename, file_data->tempname));
if (replace_file(file_data->tempname, file_data->filename)) {
log_warn(LD_FS, "Error replacing \"%s\": %s", file_data->filename,
strerror(errno));
r = -1;
}
}
}
tor_free(file_data->filename);
tor_free(file_data->tempname);
tor_free(file_data);
return r;
}
/** DOCDOC */
int
finish_writing_to_file(open_file_t *file_data)
{
return finish_writing_to_file_impl(file_data, 0);
}
/** DOCDOC */
int
abort_writing_to_file(open_file_t *file_data)
{
return finish_writing_to_file_impl(file_data, 1);
}
/** Helper: given a set of flags as passed to open(2), open the file
* <b>fname</b> and write all the sized_chunk_t structs in <b>chunks</b> to
* the file. Do so as atomically as possible e.g. by opening temp files and
@ -1467,53 +1567,24 @@ static int
write_chunks_to_file_impl(const char *fname, const smartlist_t *chunks,
int open_flags)
{
size_t tempname_len;
char *tempname;
int fd;
int result;
tempname_len = strlen(fname)+16;
tor_assert(tempname_len > strlen(fname)); /*check for overflow*/
tempname = tor_malloc(tempname_len);
if (open_flags & O_APPEND) {
strlcpy(tempname, fname, tempname_len);
} else {
if (tor_snprintf(tempname, tempname_len, "%s.tmp", fname)<0) {
log(LOG_WARN, LD_GENERAL, "Failed to generate filename");
goto err;
}
}
if ((fd = open(tempname, open_flags, 0600))
< 0) {
log(LOG_WARN, LD_FS, "Couldn't open \"%s\" for writing: %s", tempname,
strerror(errno));
goto err;
}
open_file_t *file = NULL;
int fd, result;
fd = start_writing_to_file(fname, open_flags, 0600, &file);
if (fd<0)
return -1;
SMARTLIST_FOREACH(chunks, sized_chunk_t *, chunk,
{
result = write_all(fd, chunk->bytes, chunk->len, 0);
if (result < 0 || (size_t)result != chunk->len) {
log(LOG_WARN, LD_FS, "Error writing to \"%s\": %s", tempname,
log(LOG_WARN, LD_FS, "Error writing to \"%s\": %s", fname,
strerror(errno));
close(fd);
goto err;
}
});
if (close(fd)) {
log(LOG_WARN, LD_FS, "Error flushing to \"%s\": %s", tempname,
strerror(errno));
goto err;
}
if (!(open_flags & O_APPEND)) {
if (replace_file(tempname, fname)) {
log(LOG_WARN, LD_FS, "Error replacing \"%s\": %s", fname,
strerror(errno));
goto err;
}
}
tor_free(tempname);
return 0;
return finish_writing_to_file(file);
err:
tor_free(tempname);
abort_writing_to_file(file);
return -1;
}

5
src/common/util.h
View File

@ -213,6 +213,11 @@ file_status_t file_status(const char *filename);
* directory; see that function's documentation for details. */
typedef enum { CPD_NONE, CPD_CREATE, CPD_CHECK } cpd_check_t;
int check_private_dir(const char *dirname, cpd_check_t check);
typedef struct open_file_t open_file_t;
int start_writing_to_file(const char *fname, int open_flags, int mode,
open_file_t **data_out);
int finish_writing_to_file(open_file_t *file_data);
int abort_writing_to_file(open_file_t *file_data);
int write_str_to_file(const char *fname, const char *str, int bin);
int write_bytes_to_file(const char *fname, const char *str, size_t len,
int bin);