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authorPeter Stephenson <p.stephenson@samsung.com>2021-08-27 09:36:06 +0100
committerPeter Stephenson <p.stephenson@samsung.com>2021-08-27 09:36:06 +0100
commite5cd2dd980302f328d232d933f646c3dc02828bf (patch)
treece6f58610a53c0f9a6d8b82957eaba440d22c78d
parent1a78e46564d7e480affb7f832b33605c13a01e55 (diff)
downloadzsh-e5cd2dd980302f328d232d933f646c3dc02828bf.tar.gz
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49290: Replace stdio for buffered shell input.
The previous method allowed memory management to interact with signal handlers, causing occasional crashes on some system. Instead, use a simple pre-allocated buffer and raw system calls.
-rw-r--r--ChangeLog6
-rw-r--r--Src/init.c14
-rw-r--r--Src/input.c122
3 files changed, 123 insertions, 19 deletions
diff --git a/ChangeLog b/ChangeLog
index 458446401..dd7b630d0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2021-08-27 Peter Stephenson <p.stephenson@samsung.com>
+
+ * 49290: Src/init.c, Src/input.c: Replace stdio for buffered
+ shell input to avoid memory management interacting with signal
+ handlers.
+
2021-08-27 Oliver Kiddle <opk@zsh.org>
* Marlon: 49272: Completion/Base/Utility/_call_program:
diff --git a/Src/init.c b/Src/init.c
index 3d6c94d04..878a53a37 100644
--- a/Src/init.c
+++ b/Src/init.c
@@ -1229,7 +1229,7 @@ setupshin(char *runscript)
/*
* Finish setting up SHIN and its relatives.
*/
- bshin = SHIN ? fdopen(SHIN, "r") : stdin;
+ shinbufalloc();
if (isset(SHINSTDIN) && !SHIN && unset(INTERACTIVE)) {
#ifdef _IONBF
setvbuf(stdin, NULL, _IONBF, 0);
@@ -1384,9 +1384,9 @@ init_misc(char *cmd, char *zsh_name)
dosetopt(RESTRICTED, 1, 0, opts);
if (cmd) {
if (SHIN >= 10)
- fclose(bshin);
+ close(SHIN);
SHIN = movefd(open("/dev/null", O_RDONLY | O_NOCTTY));
- bshin = fdopen(SHIN, "r");
+ shinbufreset();
execstring(cmd, 0, 1, "cmdarg");
stopmsg = 1;
zexit((exit_pending || shell_exiting) ? exit_val : lastval, ZEXIT_NORMAL);
@@ -1409,7 +1409,6 @@ source(char *s)
int tempfd = -1, fd, cj;
zlong oldlineno;
int oldshst, osubsh, oloops;
- FILE *obshin;
char *old_scriptname = scriptname, *us;
char *old_scriptfilename = scriptfilename;
unsigned char *ocs;
@@ -1426,7 +1425,6 @@ source(char *s)
/* save the current shell state */
fd = SHIN; /* store the shell input fd */
- obshin = bshin; /* store file handle for buffered shell input */
osubsh = subsh; /* store whether we are in a subshell */
cj = thisjob; /* store our current job number */
oldlineno = lineno; /* store our current lineno */
@@ -1439,7 +1437,7 @@ source(char *s)
if (!prog) {
SHIN = tempfd;
- bshin = fdopen(SHIN, "r");
+ shinbufsave();
}
subsh = 0;
lineno = 1;
@@ -1507,10 +1505,10 @@ source(char *s)
if (prog)
freeeprog(prog);
else {
- fclose(bshin);
+ close(SHIN);
fdtable[SHIN] = FDT_UNUSED;
SHIN = fd; /* the shell input fd */
- bshin = obshin; /* file handle for buffered shell input */
+ shinbufrestore();
}
subsh = osubsh; /* whether we are in a subshell */
thisjob = cj; /* current job number */
diff --git a/Src/input.c b/Src/input.c
index f568cc135..3c6ad7002 100644
--- a/Src/input.c
+++ b/Src/input.c
@@ -80,11 +80,6 @@
/**/
int SHIN;
-/* buffered shell input for non-interactive shells */
-
-/**/
-FILE *bshin;
-
/* != 0 means we are reading input from a string */
/**/
@@ -129,7 +124,116 @@ static struct instacks *instack, *instacktop;
static int instacksz = INSTACK_INITIAL;
-/* Read a line from bshin. Convert tokens and *
+/* Size of buffer for non-interactive command input */
+
+#define SHINBUFSIZE 8192
+
+/* Input buffer for non-interactive command input */
+static char *shinbuffer;
+
+/* Pointer into shinbuffer */
+static char *shinbufptr;
+
+/* End of contents read into shinbuffer */
+static char *shinbufendptr;
+
+/* Entry on SHIN buffer save stack */
+struct shinsaveentry {
+ /* Next entry on stack */
+ struct shinsaveentry *next;
+ /* Saved shinbuffer */
+ char *buffer;
+ /* Saved shinbufptr */
+ char *ptr;
+ /* Saved shinbufendptr */
+ char *endptr;
+};
+
+/* SHIN buffer save stack */
+struct shinsaveentry *shinsavestack;
+
+/* Reset the input buffer for SHIN, discarding any pending input */
+
+/**/
+void
+shinbufreset(void)
+{
+ shinbufendptr = shinbufptr = shinbuffer;
+}
+
+/* Allocate a new shinbuffer
+ *
+ * Only called at shell initialisation and when saving on the stack.
+ */
+
+/**/
+void
+shinbufalloc(void)
+{
+ shinbuffer = zalloc(SHINBUFSIZE);
+ shinbufreset();
+}
+
+/* Save entry on SHIN buffer save stack */
+
+/**/
+void
+shinbufsave(void)
+{
+ struct shinsaveentry *entry =
+ (struct shinsaveentry *)zalloc(sizeof(struct shinsaveentry));
+
+ entry->next = shinsavestack;
+ entry->buffer = shinbuffer;
+ entry->ptr = shinbufptr;
+ entry->endptr = shinbufendptr;
+
+ shinsavestack = entry;
+
+ shinbufalloc();
+}
+
+/* Restore entry from SHIN buffer save stack */
+
+/**/
+void
+shinbufrestore(void)
+{
+ struct shinsaveentry *entry = shinsavestack;
+
+ zfree(shinbuffer, SHINBUFSIZE);
+
+ shinbuffer = entry->buffer;
+ shinbufptr = entry->ptr;
+ shinbufendptr = entry->endptr;
+
+ shinsavestack = entry->next;
+ zfree(entry, sizeof(struct shinsaveentry));
+}
+
+/* Get a character from SHIN, -1 if none available */
+
+/**/
+static int
+shingetchar(void)
+{
+ int nread;
+
+ if (shinbufptr < shinbufendptr)
+ return STOUC(*shinbufptr++);
+
+ shinbufreset();
+ do {
+ errno = 0;
+ nread = read(SHIN, shinbuffer, SHINBUFSIZE);
+ } while (nread < 0 && errno == EINTR);
+ if (nread <= 0)
+ return -1;
+ shinbufendptr = shinbuffer + nread;
+ return STOUC(*shinbufptr++);
+}
+
+/* Read a line from SHIN. Convert tokens and *
* null characters to Meta c^32 character pairs. */
/**/
@@ -147,11 +251,7 @@ shingetline(void)
winch_unblock();
dont_queue_signals();
for (;;) {
- /* Can't fgets() here because we need to accept '\0' bytes */
- do {
- errno = 0;
- c = fgetc(bshin);
- } while (c < 0 && errno == EINTR);
+ c = shingetchar();
if (c < 0 || c == '\n') {
winch_block();
restore_queue_signals(q);