Impose limit on maximum line length, controlled by option.

2 files changed, 38 insertions, 5 deletions

diff --git a/pw.1 b/pw.1
index 5a580db..a333a9f 100644
--- a/pw.1
+++ b/pw.1
@@ -564,6 +564,19 @@ to the specified decimal integer value. The default value is 15.
 This value must be positive, and is clipped to the number of display lines
 available in the terminal, less one.
 
+.IP "\fB-m\fP \fIinteger\fP"
+Set the maximum line length to
+.IR integer .
+The default value is 4095. Values smaller than 72 are adjusted to 72.
+The length is measured in display characters, not original characters.
+A control character like
+.B ^C
+counts as two characters. The behavior of
+.I pw
+is that when it is collecting a line, and the line has reached the maximum
+length, it keeps reading characters from the standard input, but discards
+them, while remaining responsive to TTY input.
+
 .IP \fB-d\fP
 Disable auto-quit: when no more input is available, instead of updating
 the display one last time and terminating,
diff --git a/pw.c b/pw.c
index 6538cbd..f25a414 100644
--- a/pw.c
+++ b/pw.c
@@ -28,6 +28,7 @@
 #include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdint.h>
 #include <ctype.h>
 #include <string.h>
 #include <limits.h>
@@ -51,6 +52,7 @@
 #define DEL 127
 
 #define min(a, b) ((a) < (b) ? (a) : (b))
+#define max(a, b) ((a) > (b) ? (a) : (b))
 
 #ifdef __GNUC__
 #define printf_attr(fmtpos, vargpos) __attribute__ ((format (printf, \
@@ -151,8 +153,11 @@ static void dsdrop(char *str)
 
 static size_t dslen(const char *str)
 {
-  const dstr *ds = dstr_of(str);
-  return ds->len;
+  if (str) {
+    const dstr *ds = dstr_of(str);
+    return ds->len;
+  }
+  return 0;
 }
 
 static char *dsgrow(char *str, size_t len)
@@ -691,6 +696,7 @@ int main(int argc, char **argv)
   unsigned stat = 0;
   FILE *tty = fopen("/dev/tty", "r+");
   int maxlines = 15, nlines = 0, maxed = 0;
+  size_t maxlen = 2047;
   int opt;
   int ifd = fileno(stdin);
   int ttyfd = tty ? fileno(tty) : -1;
@@ -728,7 +734,7 @@ int main(int argc, char **argv)
     }
   }
 
-  while ((opt = getopt(argc, argv, "n:i:l:dEBg:q:")) != -1) {
+  while ((opt = getopt(argc, argv, "n:i:l:dEBg:q:m:")) != -1) {
     switch (opt) {
     case 'n':
       {
@@ -802,6 +808,20 @@ int main(int argc, char **argv)
         stat |= stat_grep;
       }
       break;
+    case 'm':
+      {
+        char *err;
+        int val = getzp(optarg, &err);
+        if (val < 0) {
+          error("-%c option: bad value %s: %s\n", opt, optarg, err);
+          return EXIT_FAILURE;
+        }
+
+        if ((int) (size_t) val != val)
+          val = -1;
+        maxlen = max(72, val);
+      }
+      break;
     default:
       usage();
     }
@@ -865,7 +885,7 @@ int main(int argc, char **argv)
 
     if ((stat & stat_eof) == 0) {
       int ch;
-      while ((ch = getc(stdin)) != EOF && ch != '\n')
+      while ((ch = getc(stdin)) != EOF && ch != '\n' && dslen(line) < maxlen)
         line = addchesc(line, ch);
       if (ch == EOF) {
         if (feof(stdin) || (errno != EAGAIN && errno != EWOULDBLOCK)) {
@@ -882,7 +902,7 @@ int main(int argc, char **argv)
           drawstatus(hist, columns, stat, curcmd);
         }
         clearerr(stdin);
-      } else {
+      } else if (ch == '\n') {
         nfds = 1;
         line = addch(line, 0);
         if ((stat & stat_grep)) {