libbb: revent previous version of "concurrent history updating"
and replace it with one which does not "snoop" history written
by others. (1) it is what bug 185 needs, and (2) it is less bloaty:
function old new delta
load_history - 252 +252
read_line_input 3155 3287 +132
next_token 914 918 +4
qrealloc 36 33 -3
getoptscmd 713 708 -5
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/2 up/down: 388/-8) Total: 380 bytes
diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index af1b627..7bcdb95 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -954,6 +954,14 @@
#endif /* FEATURE_COMMAND_TAB_COMPLETION */
+line_input_t* FAST_FUNC new_line_input_t(int flags)
+{
+ line_input_t *n = xzalloc(sizeof(*n));
+ n->flags = flags;
+ return n;
+}
+
+
#if MAX_HISTORY > 0
static void save_command_ps_at_cur_history(void)
@@ -991,16 +999,23 @@
#if ENABLE_FEATURE_EDITING_SAVEHISTORY
/* We try to ensure that concurrent additions to the history
- * do not overwrite each other, and that additions to the history
- * by one user are noticed by others.
+ * do not overwrite each other.
* Otherwise shell users get unhappy.
*
* History file is trimmed lazily, when it grows several times longer
* than configured MAX_HISTORY lines.
*/
+static void free_line_input_t(line_input_t *n)
+{
+ int i = n->cnt_history;
+ while (i > 0)
+ free(n->history[--i]);
+ free(n);
+}
+
/* state->flags is already checked to be nonzero */
-static void load_history(void)
+static void load_history(line_input_t *st_parm)
{
char *temp_h[MAX_HISTORY];
char *line;
@@ -1009,18 +1024,18 @@
/* NB: do not trash old history if file can't be opened */
- fp = fopen_for_read(state->hist_file);
+ fp = fopen_for_read(st_parm->hist_file);
if (fp) {
/* clean up old history */
- for (idx = state->cnt_history; idx > 0;) {
+ for (idx = st_parm->cnt_history; idx > 0;) {
idx--;
- free(state->history[idx]);
- state->history[idx] = NULL;
+ free(st_parm->history[idx]);
+ st_parm->history[idx] = NULL;
}
/* fill temp_h[], retaining only last MAX_HISTORY lines */
memset(temp_h, 0, sizeof(temp_h));
- state->cnt_history_in_file = idx = 0;
+ st_parm->cnt_history_in_file = idx = 0;
while ((line = xmalloc_fgetline(fp)) != NULL) {
if (line[0] == '\0') {
free(line);
@@ -1028,16 +1043,15 @@
}
free(temp_h[idx]);
temp_h[idx] = line;
- state->cnt_history_in_file++;
+ st_parm->cnt_history_in_file++;
idx++;
if (idx == MAX_HISTORY)
idx = 0;
}
- state->last_history_end = lseek(fileno(fp), 0, SEEK_CUR);
fclose(fp);
/* find first non-NULL temp_h[], if any */
- if (state->cnt_history_in_file) {
+ if (st_parm->cnt_history_in_file) {
while (temp_h[idx] == NULL) {
idx++;
if (idx == MAX_HISTORY)
@@ -1045,7 +1059,7 @@
}
}
- /* copy temp_h[] to state->history[] */
+ /* copy temp_h[] to st_parm->history[] */
for (i = 0; i < MAX_HISTORY;) {
line = temp_h[idx];
if (!line)
@@ -1056,71 +1070,60 @@
line_len = strlen(line);
if (line_len >= MAX_LINELEN)
line[MAX_LINELEN-1] = '\0';
- state->history[i++] = line;
+ st_parm->history[i++] = line;
}
- state->cnt_history = i;
+ st_parm->cnt_history = i;
}
}
/* state->flags is already checked to be nonzero */
static void save_history(char *str)
{
- off_t end;
int fd;
- int len;
+ int len, len2;
- len = strlen(str);
- again:
fd = open(state->hist_file, O_WRONLY | O_CREAT | O_APPEND, 0666);
if (fd < 0)
return;
-
- end = lseek(fd, 0, SEEK_END);
-
- if (str) {
- str[len] = '\n';
- full_write(fd, str, len + 1);
- str[len] = '\0';
- str = NULL;
- state->cnt_history_in_file++;
- }
+ xlseek(fd, 0, SEEK_END); /* paranoia */
+ len = strlen(str);
+ str[len] = '\n'; /* we (try to) do atomic write */
+ len2 = full_write(fd, str, len + 1);
+ str[len] = '\0';
close(fd);
-
- /* if it was not a 1st write */
- if (state->last_history_end >= 0) {
- /* did someone else write anything there? */
- if (state->last_history_end != end) {
- load_history(); /* note: updates cnt_history_in_file */
- state->last_history_end = -1;
- goto again;
- }
- }
- state->last_history_end = end + len + 1;
+ if (len2 != len + 1)
+ return; /* "wtf?" */
/* did we write so much that history file needs trimming? */
+ state->cnt_history_in_file++;
if (state->cnt_history_in_file > MAX_HISTORY * 4) {
FILE *fp;
char *new_name;
+ line_input_t *st_temp;
+ int i;
- new_name = xasprintf("%s.new", state->hist_file);
+ /* we may have concurrently written entries from others.
+ * load them */
+ st_temp = new_line_input_t(state->flags);
+ st_temp->hist_file = state->hist_file;
+ load_history(st_temp);
+
+ /* write out temp file and replace hist_file atomically */
+ new_name = xasprintf("%s.%u.new", state->hist_file, (int) getpid());
fp = fopen_for_write(new_name);
if (fp) {
- int i;
-
- for (i = 0; i < state->cnt_history; i++) {
- fprintf(fp, "%s\n", state->history[i]);
- }
- state->cnt_history_in_file = i; /* == cnt_history */
- state->last_history_end = lseek(fileno(fp), 0, SEEK_CUR);
+ for (i = 0; i < st_temp->cnt_history; i++)
+ fprintf(fp, "%s\n", st_temp->history[i]);
fclose(fp);
- /* replace hist_file atomically */
- rename(new_name, state->hist_file);
+ if (rename(new_name, state->hist_file) == 0)
+ state->cnt_history_in_file = st_temp->cnt_history;
}
free(new_name);
+ free_line_input_t(st_temp);
}
}
#else
-#define load_history() ((void)0)
+#define load_history(a) ((void)0)
#define save_history(a) ((void)0)
#endif /* FEATURE_COMMAND_SAVEHISTORY */
@@ -1490,7 +1493,8 @@
state = st ? st : (line_input_t*) &const_int_0;
#if ENABLE_FEATURE_EDITING_SAVEHISTORY
if ((state->flags & SAVE_HISTORY) && state->hist_file)
- load_history();
+ if (state->cnt_history == 0)
+ load_history(state);
#endif
if (state->flags & DO_HISTORY)
state->cur_history = state->cnt_history;
@@ -1948,14 +1952,6 @@
return len; /* can't return command_len, DEINIT_S() destroys it */
}
-line_input_t* FAST_FUNC new_line_input_t(int flags)
-{
- line_input_t *n = xzalloc(sizeof(*n));
- n->flags = flags;
- n->last_history_end = -1;
- return n;
-}
-
#else
#undef read_line_input