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libbb: revent previous version of "concurrent history updating"

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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
This commit is contained in:
Denis Vlasenko 2009-03-23 06:33:37 +00:00
parent ddbee974b4
commit c0ea82a457
2 changed files with 56 additions and 60 deletions
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2
include/libbb.h
View File

@ -1199,7 +1199,6 @@ typedef struct line_input_t {
int cur_history;
#if ENABLE_FEATURE_EDITING_SAVEHISTORY
unsigned cnt_history_in_file;
off_t last_history_end;
const char *hist_file;
#endif
char *history[MAX_HISTORY + 1];
@ -1215,6 +1214,7 @@ enum {
FOR_SHELL = DO_HISTORY | SAVE_HISTORY | TAB_COMPLETION | USERNAME_COMPLETION,
};
line_input_t *new_line_input_t(int flags) FAST_FUNC;
/* so far static: void free_line_input_t(line_input_t *n) FAST_FUNC; */
/* Returns:
* -1 on read errors or EOF, or on bare Ctrl-D,
* 0 on ctrl-C (the line entered is still returned in 'command'),

114
libbb/lineedit.c
View File

@ -954,6 +954,14 @@ static void input_tab(smallint *lastWasTab)
#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 @@ static int get_next_history(void)
#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 @@ static void load_history(void)
/* 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 @@ static void load_history(void)
}
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 @@ static void load_history(void)
}
}
/* 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 @@ static void load_history(void)
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 @@ int FAST_FUNC read_line_input(const char *prompt, char *command, int maxsize, li
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 @@ int FAST_FUNC read_line_input(const char *prompt, char *command, int maxsize, li
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