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authorDenys Vlasenko <vda.linux@googlemail.com>2011-02-07 02:03:51 +0100
committerDenys Vlasenko <vda.linux@googlemail.com>2011-02-07 02:03:51 +0100
commit8ee2adab21328761b80e0cbc513eda7eaa880b24 (patch)
treec771696ab3b1be735e831b1721ab751c874e1cd3 /coreutils/echo.c
parentb8ab4b038803df195eee9844c3597dd640c00393 (diff)
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echo: do not retry on write errors
function old new delta echo_main 297 336 +39 stpcpy - 22 +22 run_pipe 1561 1566 +5 pseudo_exec_argv 187 192 +5 hush_exit 75 80 +5 ------------------------------------------------------------------------------ (add/remove: 3/0 grow/shrink: 4/0 up/down: 98/0) Total: 76 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'coreutils/echo.c')
-rw-r--r--coreutils/echo.c87
1 files changed, 48 insertions, 39 deletions
diff --git a/coreutils/echo.c b/coreutils/echo.c
index 3821e594e..5fa3d10c5 100644
--- a/coreutils/echo.c
+++ b/coreutils/echo.c
@@ -29,46 +29,42 @@
29 29
30/* NB: can be used by shell even if not enabled as applet */ 30/* NB: can be used by shell even if not enabled as applet */
31 31
32/*
33 * NB2: we don't use stdio, we need better error handing.
34 * Examples include writing into non-opened stdout and error on write.
35 *
36 * With stdio, output gets shoveled into stdout buffer, and even
37 * fflush cannot clear it out. It seems that even if libc receives
38 * EBADF on write attempts, it feels determined to output data no matter what.
39 * If echo is called by shell, it will try writing again later, and possibly
40 * will clobber future output. Not good.
41 *
42 * Solaris has fpurge which discards buffered input. glibc has __fpurge.
43 * But this function is not standard.
44 */
45
32int echo_main(int argc UNUSED_PARAM, char **argv) 46int echo_main(int argc UNUSED_PARAM, char **argv)
33{ 47{
48 char **pp;
34 const char *arg; 49 const char *arg;
50 char *out;
51 char *buffer;
52 unsigned buflen;
53 int r;
35#if !ENABLE_FEATURE_FANCY_ECHO 54#if !ENABLE_FEATURE_FANCY_ECHO
36 enum { 55 enum {
37 eflag = '\\', 56 eflag = '\\',
38 nflag = 1, /* 1 -- print '\n' */ 57 nflag = 1, /* 1 -- print '\n' */
39 }; 58 };
40 59
41 /* We must check that stdout is not closed. 60 argv++;
42 * The reason for this is highly non-obvious.
43 * echo_main is used from shell. Shell must correctly handle "echo foo"
44 * if stdout is closed. With stdio, output gets shoveled into
45 * stdout buffer, and even fflush cannot clear it out. It seems that
46 * even if libc receives EBADF on write attempts, it feels determined
47 * to output data no matter what. So it will try later,
48 * and possibly will clobber future output. Not good. */
49// TODO: check fcntl() & O_ACCMODE == O_WRONLY or O_RDWR?
50 if (fcntl(1, F_GETFL) == -1)
51 return 1; /* match coreutils 6.10 (sans error msg to stderr) */
52 //if (dup2(1, 1) != 1) - old way
53 // return 1;
54
55 arg = *++argv;
56 if (!arg)
57 goto newline_ret;
58#else 61#else
59 const char *p; 62 const char *p;
60 char nflag = 1; 63 char nflag = 1;
61 char eflag = 0; 64 char eflag = 0;
62 65
63 /* We must check that stdout is not closed. */ 66 while ((arg = *++argv) != NULL) {
64 if (fcntl(1, F_GETFL) == -1) 67 if (!arg || arg[0] != '-')
65 return 1;
66
67 while (1) {
68 arg = *++argv;
69 if (!arg)
70 goto newline_ret;
71 if (*arg != '-')
72 break; 68 break;
73 69
74 /* If it appears that we are handling options, then make sure 70 /* If it appears that we are handling options, then make sure
@@ -77,7 +73,7 @@ int echo_main(int argc UNUSED_PARAM, char **argv)
77 */ 73 */
78 p = arg + 1; 74 p = arg + 1;
79 if (!*p) /* A single '-', so echo it. */ 75 if (!*p) /* A single '-', so echo it. */
80 goto just_echo; 76 break;
81 77
82 do { 78 do {
83 if (!strrchr("neE", *p)) 79 if (!strrchr("neE", *p))
@@ -95,19 +91,27 @@ int echo_main(int argc UNUSED_PARAM, char **argv)
95 } 91 }
96 just_echo: 92 just_echo:
97#endif 93#endif
98 while (1) { 94
99 /* arg is already == *argv and isn't NULL */ 95 buflen = 1;
96 pp = argv;
97 while ((arg = *pp) != NULL) {
98 buflen += strlen(arg) + 1;
99 pp++;
100 }
101 out = buffer = xmalloc(buflen);
102
103 while ((arg = *argv) != NULL) {
100 int c; 104 int c;
101 105
102 if (!eflag) { 106 if (!eflag) {
103 /* optimization for very common case */ 107 /* optimization for very common case */
104 fputs(arg, stdout); 108 out = stpcpy(out, arg);
105 } else while ((c = *arg++)) { 109 } else while ((c = *arg++)) {
106 if (c == eflag) { /* Check for escape seq. */ 110 if (c == eflag) { /* Check for escape seq. */
107 if (*arg == 'c') { 111 if (*arg == 'c') {
108 /* '\c' means cancel newline and 112 /* '\c' means cancel newline and
109 * ignore all subsequent chars. */ 113 * ignore all subsequent chars. */
110 goto ret; 114 goto do_write;
111 } 115 }
112#if !ENABLE_FEATURE_FANCY_ECHO 116#if !ENABLE_FEATURE_FANCY_ECHO
113 /* SUSv3 specifies that octal escapes must begin with '0'. */ 117 /* SUSv3 specifies that octal escapes must begin with '0'. */
@@ -127,21 +131,26 @@ int echo_main(int argc UNUSED_PARAM, char **argv)
127 c = bb_process_escape_sequence(&arg); 131 c = bb_process_escape_sequence(&arg);
128 } 132 }
129 } 133 }
130 bb_putchar(c); 134 *out++ = c;
131 } 135 }
132 136
133 arg = *++argv; 137 if (!*++argv)
134 if (!arg)
135 break; 138 break;
136 bb_putchar(' '); 139 *out++ = ' ';
137 } 140 }
138 141
139 newline_ret:
140 if (nflag) { 142 if (nflag) {
141 bb_putchar('\n'); 143 *out++ = '\n';
142 } 144 }
143 ret: 145
144 return fflush_all(); 146 do_write:
147 r = full_write(STDOUT_FILENO, buffer, out - buffer);
148 free(buffer);
149 if (r < 0) {
150 bb_perror_msg(bb_msg_write_error);
151 return 1;
152 }
153 return 0;
145} 154}
146 155
147/*- 156/*-