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authorDenis Vlasenko2007-11-22 08:16:57 +0000
committerDenis Vlasenko2007-11-22 08:16:57 +0000
commit7d75a96b15327050a294b1f54981781ce6e551e2 (patch)
treedf8a1fcb74b6bd7869fe60af461c11f0684df043 /coreutils/echo.c
parent705eaf8b403555741cf6313a76da8597ae54d324 (diff)
downloadbusybox-7d75a96b15327050a294b1f54981781ce6e551e2.zip
busybox-7d75a96b15327050a294b1f54981781ce6e551e2.tar.gz
ash: fix bug where redirection of closed fd was leaving it open afterwards.
redirect 983 1024 +41 bb_echo 276 301 +25 popredir 118 132 +14 evalcommand 1163 1176 +13 bbunpack 358 366 +8 echocmd 13 5 -8 echo_main 13 5 -8 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 5/2 up/down: 101/-16) Total: 85 bytes text data bss dec hex filename 774999 962 9236 785197 bfb2d busybox_old 775084 962 9236 785282 bfb82 busybox_unstripped
Diffstat (limited to 'coreutils/echo.c')
-rw-r--r--coreutils/echo.c141
1 files changed, 139 insertions, 2 deletions
diff --git a/coreutils/echo.c b/coreutils/echo.c
index 860853f..4c7a917 100644
--- a/coreutils/echo.c
+++ b/coreutils/echo.c
@@ -25,7 +25,9 @@
#include "libbb.h"
-int bb_echo(char **argv)
+/* argc is unused, but removing it precludes compiler from
+ * using call -> jump optimization */
+int bb_echo(int argc, char **argv)
{
const char *arg;
#if !ENABLE_FEATURE_FANCY_ECHO
@@ -33,6 +35,18 @@ int bb_echo(char **argv)
eflag = '\\',
nflag = 1, /* 1 -- print '\n' */
};
+
+ /* We must check that stdout is not closed.
+ * The reason for this is highly non-obvious.
+ * bb_echo is used from shell. Shell must correctly handle "echo foo"
+ * if stdout is closed. With stdio, output gets shoveled into
+ * stdout buffer, and even fflush cannot clear it out. It seems that
+ * even if libc receives EBADF on write attempts, it feels determined
+ * to output data no matter what. So it will try later,
+ * and possibly will clobber future output. Not good. */
+ if (dup2(1, 1) != 1)
+ return -1;
+
arg = *++argv;
if (!arg)
goto newline_ret;
@@ -41,6 +55,10 @@ int bb_echo(char **argv)
char nflag = 1;
char eflag = 0;
+ /* We must check that stdout is not closed. */
+ if (dup2(1, 1) != 1)
+ return -1;
+
while (1) {
arg = *++argv;
if (!arg)
@@ -122,7 +140,7 @@ int bb_echo(char **argv)
int echo_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int echo_main(int argc, char **argv)
{
- return bb_echo(argv);
+ return bb_echo(argc, argv);
}
/*-
@@ -163,3 +181,122 @@ int echo_main(int argc, char **argv)
*
* @(#)echo.c 8.1 (Berkeley) 5/31/93
*/
+
+#ifdef VERSION_WITH_WRITEV
+/* We can't use stdio.
+ * The reason for this is highly non-obvious.
+ * bb_echo is used from shell. Shell must correctly handle "echo foo"
+ * if stdout is closed. With stdio, output gets shoveled into
+ * stdout buffer, and even fflush cannot clear it out. It seems that
+ * even if libc receives EBADF on write attempts, it feels determined
+ * to output data no matter what. So it will try later,
+ * and possibly will clobber future output. Not good.
+ *
+ * Using writev instead, with 'direct' conversion of argv vector.
+ */
+
+int bb_echo(int argc, char **argv)
+{
+ struct iovec io[argc];
+ struct iovec *cur_io = io;
+ char *arg;
+ char *p;
+#if !ENABLE_FEATURE_FANCY_ECHO
+ enum {
+ eflag = '\\',
+ nflag = 1, /* 1 -- print '\n' */
+ };
+ arg = *++argv;
+ if (!arg)
+ goto newline_ret;
+#else
+ char nflag = 1;
+ char eflag = 0;
+
+ while (1) {
+ arg = *++argv;
+ if (!arg)
+ goto newline_ret;
+ if (*arg != '-')
+ break;
+
+ /* If it appears that we are handling options, then make sure
+ * that all of the options specified are actually valid.
+ * Otherwise, the string should just be echoed.
+ */
+ p = arg + 1;
+ if (!*p) /* A single '-', so echo it. */
+ goto just_echo;
+
+ do {
+ if (!strrchr("neE", *p))
+ goto just_echo;
+ } while (*++p);
+
+ /* All of the options in this arg are valid, so handle them. */
+ p = arg + 1;
+ do {
+ if (*p == 'n')
+ nflag = 0;
+ if (*p == 'e')
+ eflag = '\\';
+ } while (*++p);
+ }
+ just_echo:
+#endif
+
+ while (1) {
+ /* arg is already == *argv and isn't NULL */
+ int c;
+
+ cur_io->iov_base = p = arg;
+
+ if (!eflag) {
+ /* optimization for very common case */
+ p += strlen(arg);
+ } else while ((c = *arg++)) {
+ if (c == eflag) { /* Check for escape seq. */
+ if (*arg == 'c') {
+ /* '\c' means cancel newline and
+ * ignore all subsequent chars. */
+ cur_io->iov_len = p - (char*)cur_io->iov_base;
+ cur_io++;
+ goto ret;
+ }
+#if !ENABLE_FEATURE_FANCY_ECHO
+ /* SUSv3 specifies that octal escapes must begin with '0'. */
+ if ( (((unsigned char)*arg) - '1') >= 7)
+#endif
+ {
+ /* Since SUSv3 mandates a first digit of 0, 4-digit octals
+ * of the form \0### are accepted. */
+ if (*arg == '0' && ((unsigned char)(arg[1]) - '0') < 8) {
+ arg++;
+ }
+ /* bb_process_escape_sequence can handle nul correctly */
+ c = bb_process_escape_sequence( (void*) &arg);
+ }
+ }
+ *p++ = c;
+ }
+
+ arg = *++argv;
+ if (arg)
+ *p++ = ' ';
+ cur_io->iov_len = p - (char*)cur_io->iov_base;
+ cur_io++;
+ if (!arg)
+ break;
+ }
+
+ newline_ret:
+ if (nflag) {
+ cur_io->iov_base = (char*)"\n";
+ cur_io->iov_len = 1;
+ cur_io++;
+ }
+ ret:
+ /* TODO: implement and use full_writev? */
+ return writev(1, io, (cur_io - io)) >= 0;
+}
+#endif