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From: =?utf-8?b?0L3QsNCx?= <nabijaczleweli@nabijaczleweli.xyz>
Date: Wed, 15 Mar 2023 16:16:48 +0100
Subject: wall: use fputs_careful()
LINE_MAX only applies to teletypes in canonical mode: when stdin is a
file, it could still very much tear; start off at 512 for the sprintf(),
then use getline() like in write.
The line wrapping has one suboptimal edge-case:
$ wall < all
Broadcast message from nabijaczleweli@tarta (pts/4) (Tue Mar 14 22:31:25
2023):
^N^O^P^Q^R^S^T^U^V^W^X^Y^Z^[^\^]^^^_
!"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJ
KLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{|}~^?\200\201\202\203\204\205\206
\207\210\211\212\213\214\215\216\217\220\221\222\223\224\225\226\227\230\231\232
\233\234\235\236\237\240\241\242\243\244\245\246\247\250\251\252\253\254\255\256
\257\260\261\262\263\264\265\266\267\270\271\272\273\274\275\276\277\300\301\302
\303\304\305\306\307\310\311\312\313\314\315\316\317\320\321\322\323\324\325\326
\327\330\331\332\333\334\335\336\337\340\341\342\343\344\345\346\347\350\351\352
\353\354\355\356\357\360\361\362\363\364\365\366\367\370\371\372\373\374\375\376
\377
but that's a pathological input, and the result is still infinitely
better than it was before, so fixing that is more trouble than it's
worth.
Bug-Debian: https://bugs.debian.org/826596
---
include/carefulputc.h | 42 +++++++++++++++++++++++++++++++++---------
login-utils/last.c | 2 +-
term-utils/wall.c | 38 ++++++--------------------------------
term-utils/write.c | 2 +-
4 files changed, 41 insertions(+), 43 deletions(-)
diff --git a/include/carefulputc.h b/include/carefulputc.h
index 4f74526..51d1c99 100644
--- a/include/carefulputc.h
+++ b/include/carefulputc.h
@@ -6,6 +6,7 @@
#include <ctype.h>
#ifdef HAVE_WIDECHAR
#include <wctype.h>
+#include <wchar.h>
#endif
#include <stdbool.h>
@@ -15,18 +16,35 @@
* A puts() for use in write and wall (that sometimes are sgid tty).
* It avoids control and invalid characters.
* The locale of the recipient is nominally unknown,
- * but it's a solid bet that the encoding is compatible with the author's.
+ * but it's a solid bet that it's compatible with the author's.
+ * Use soft_width=0 to disable wrapping.
*/
-static inline int fputs_careful(const char * s, FILE *fp, const char ctrl, bool cr_lf)
+static inline int fputs_careful(const char * s, FILE *fp, const char ctrl, bool cr_lf, int soft_width)
{
- int ret = 0;
+ int ret = 0, col = 0;
for (size_t slen = strlen(s); *s; ++s, --slen) {
- if (*s == '\n')
+ if (*s == '\t')
+ col += (7 - (col % 8)) - 1;
+ else if (*s == '\r')
+ col = -1;
+ else if (*s == '\a')
+ --col;
+
+ if ((soft_width && col >= soft_width) || *s == '\n') {
+ if (soft_width) {
+ fprintf(fp, "%*s", soft_width - col, "");
+ col = 0;
+ }
ret = fputs(cr_lf ? "\r\n" : "\n", fp);
- else if (isprint(*s) || *s == '\a' || *s == '\t' || *s == '\r')
+ if (*s == '\n' || ret < 0)
+ goto wrote;
+ }
+
+ if (isprint(*s) || *s == '\a' || *s == '\t' || *s == '\r') {
ret = putc(*s, fp);
- else if (!c_isascii(*s)) {
+ ++col;
+ } else if (!c_isascii(*s)) {
#ifdef HAVE_WIDECHAR
wchar_t w;
size_t clen = mbtowc(&w, s, slen);
@@ -35,21 +53,27 @@ static inline int fputs_careful(const char * s, FILE *fp, const char ctrl, bool
case (size_t)-1: // EILSEQ
mbtowc(NULL, NULL, 0);
nonprint:
- ret = fprintf(fp, "\\%3hho", *s);
+ col += ret = fprintf(fp, "\\%3hho", *s);
break;
default:
if(!iswprint(w))
goto nonprint;
ret = fwrite(s, 1, clen, fp);
+ if (soft_width)
+ col += wcwidth(w);
s += clen - 1;
slen -= clen - 1;
break;
}
#else
- ret = fprintf(fp, "\\%3hho", *s);
+ col += ret = fprintf(fp, "\\%3hho", *s);
#endif
- } else
+ } else {
ret = fputs((char[]){ ctrl, *s ^ 0x40, '\0' }, fp);
+ col += 2;
+ }
+
+ wrote:
if (ret < 0)
return EOF;
}
diff --git a/login-utils/last.c b/login-utils/last.c
index c5984f1..8386f08 100644
--- a/login-utils/last.c
+++ b/login-utils/last.c
@@ -550,7 +550,7 @@ static int list(const struct last_control *ctl, struct utmpx *p, time_t logout_t
/*
* Print out "final" string safely.
*/
- fputs_careful(final, stdout, '*', false);
+ fputs_careful(final, stdout, '*', false, 0);
if (len < 0 || (size_t)len >= sizeof(final))
putchar('\n');
diff --git a/term-utils/wall.c b/term-utils/wall.c
index 97623b8..fa5e027 100644
--- a/term-utils/wall.c
+++ b/term-utils/wall.c
@@ -273,29 +273,13 @@ int main(int argc, char **argv)
exit(EXIT_SUCCESS);
}
-static void buf_putc_careful(FILE *fs, int c)
-{
- if (isprint(c) || c == '\a' || c == '\t' || c == '\r' || c == '\n')
- fputc(c, fs);
- else if (!c_isascii(c))
- fprintf(fs, "\\%3o", (unsigned char)c);
- else
- fputs((char[]){ '^', c ^ 0x40, '\0' }, fs);
-}
-
static char *makemsg(char *fname, char **mvec, int mvecsz,
size_t *mbufsize, int print_banner)
{
- register int ch, cnt;
- char *p, *lbuf, *retbuf;
+ char *lbuf, *retbuf;
FILE * fs = open_memstream(&retbuf, mbufsize);
- long line_max;
-
- line_max = sysconf(_SC_LINE_MAX);
- if (line_max <= 0)
- line_max = 512;
-
- lbuf = xmalloc(line_max);
+ size_t lbuflen = 512;
+ lbuf = xmalloc(lbuflen);
if (print_banner == TRUE) {
char *hostname = xgethostname();
@@ -330,7 +314,7 @@ static char *makemsg(char *fname, char **mvec, int mvecsz,
will not overflow as long as %d takes at most 100 chars */
fprintf(fs, "\r%*s\r\n", TERM_WIDTH, " ");
- snprintf(lbuf, line_max,
+ snprintf(lbuf, lbuflen,
_("Broadcast message from %s@%s (%s) (%s):"),
whom, hostname, where, date);
fprintf(fs, "%-*.*s\007\007\r\n", TERM_WIDTH, TERM_WIDTH, lbuf);
@@ -374,18 +358,8 @@ static char *makemsg(char *fname, char **mvec, int mvecsz,
/*
* Read message from stdin.
*/
- while (fgets(lbuf, line_max, stdin)) {
- for (cnt = 0, p = lbuf; (ch = *p) != '\0'; ++p, ++cnt) {
- if (cnt == TERM_WIDTH || ch == '\n') {
- fprintf(fs, "%*s\r\n", TERM_WIDTH - cnt, "");
- cnt = 0;
- }
- if (ch == '\t')
- cnt += (7 - (cnt % 8));
- if (ch != '\n')
- buf_putc_careful(fs, ch);
- }
- }
+ while (getline(&lbuf, &lbuflen, stdin) >= 0)
+ fputs_careful(lbuf, fs, '^', true, TERM_WIDTH);
}
fprintf(fs, "%*s\r\n", TERM_WIDTH, " ");
diff --git a/term-utils/write.c b/term-utils/write.c
index 710a58c..1d57fce 100644
--- a/term-utils/write.c
+++ b/term-utils/write.c
@@ -276,7 +276,7 @@ static void do_write(const struct write_control *ctl)
if (signal_received)
break;
- if (fputs_careful(line, stdout, '^', true) == EOF)
+ if (fputs_careful(line, stdout, '^', true, 0) == EOF)
err(EXIT_FAILURE, _("carefulputc failed"));
}
free(line);
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