Command line: improve robustness of conversions.

1 files changed, 100 insertions, 6 deletions

diff --git a/pw.c b/pw.c
index 342e510..6a4b5b2 100644
--- a/pw.c
+++ b/pw.c
@@ -5,6 +5,7 @@
 #include <string.h>
 #include <limits.h>
 #include <stdarg.h>
+#include <math.h>
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/poll.h>
@@ -22,6 +23,13 @@
 #define ESC 27
 #define DEL 127
 
+#ifdef __GNUC__
+#define printf_attr(fmtpos, vargpos) __attribute__ ((format (printf, \
+                                                             fmtpos, vargpos)))
+#else
+#define printf_attr(fmtpos, vargpos)
+#endif
+
 enum status_flags {
   stat_dirty = 1,   // display needs refresh
   stat_eof = 2,     // end of data reached
@@ -49,6 +57,9 @@ typedef struct dstr {
 
 #define dstr_of(str) ((dstr *) ((str) - sizeof (dstr)))
 
+static int poll_interval = 1000;
+static int long_interval = 10000;
+
 static char **snapshot;
 static int snaplines;
 static char *trigpat;
@@ -71,6 +82,7 @@ static void panic(const char *fmt, ...)
   abort();
 }
 
+printf_attr(1, 2)
 static void error(const char *fmt, ...)
 {
   va_list vl;
@@ -130,6 +142,25 @@ static char *dsdup(char *str)
   return copy;
 }
 
+printf_attr(1, 2)
+static char *dsdupf(char *fmt, ...)
+{
+  size_t len = 256, needed;
+  char *out = dsgrow(0, len);
+
+  for (;;) {
+    va_list vl;
+    va_start (vl, fmt);
+    needed = vsnprintf(out, len + 1, fmt, vl);
+    va_end (vl);
+    if (needed <= len)
+      break;
+    len = needed;
+  }
+
+  return dsgrow(out, needed);
+}
+
 static char *addch(char *line, int ch)
 {
   size_t len = line ? dslen(line) : 0;
@@ -289,6 +320,60 @@ static void redraw(char **circbuf, int nlines, int hpos,
   drawstatus(columns, stat, cmd);
 }
 
+static int getzp(const char *str, char **err)
+{
+  char *endp;
+  long val = strtol(str, &endp, 10);
+
+  if (endp == str) {
+    *err = dsdup("number expected");
+    return -1;
+  }
+
+  if (val <= 0) {
+    *err = dsdup("positive value required");
+    return -1;
+  }
+
+  if (val >= INT_MAX) {
+    *err = dsdup("unreasonably large value");
+    return -1;
+  }
+
+  return val;
+}
+
+static int getms(const char *str, char **err)
+{
+  errno = 0;
+  char *endp;
+  double sec = strtod(str, &endp);
+
+  if (endp == str) {
+    *err = dsdup("number expected");
+    return -1;
+  }
+
+  if ((sec == 0 || sec == HUGE_VAL) && errno != 0) {
+    *err = dsdup("unreasonable real value");
+    return -1;
+  }
+
+  if (sec < 0) {
+    *err = dsdup("positive value required");
+    return -1;
+  }
+
+  double msec = sec * 1000;
+
+  if (msec > (double) INT_MAX) {
+    *err = dsdupf("maximum interval is %f", INT_MAX / 1000.0);
+    return -1;
+  }
+
+  return msec;
+}
+
 static void execute(char *cmd, unsigned *pstat)
 {
   char *arg = cmd + 2 + strspn(cmd + 2, " \t");
@@ -414,8 +499,6 @@ int main(int argc, char **argv)
   char *line = 0;
   FILE *tty = fopen("/dev/tty", "r+");
   int maxlines = 15, nlines = 0;
-  int poll_interval = 1000;
-  int long_interval = 10000;
   int opt;
   int fd = fileno(stdin);
   int ttyfd = tty ? fileno(tty) : -1;
@@ -440,13 +523,24 @@ int main(int argc, char **argv)
   while ((opt = getopt(argc, argv, "n:i:l:d")) != -1) {
     switch (opt) {
     case 'n':
-      maxlines = atoi(optarg);
+      {
+        char *err;
+        if ((maxlines = getzp(optarg, &err)) < 0) {
+          error("-%c option: %s\n", opt, err);
+          return EXIT_FAILURE;
+        }
+      }
       break;
     case 'i': case 'l':
       {
-        double interval = atof(optarg) * 1000;
-        if (interval > (double) INT_MAX)
-          error("maximum interval is %f\n", INT_MAX / 1000.0);
+        char *err;
+        int interval = getms(optarg, &err);
+
+        if (interval < 0) {
+          error("-%c option: %s\n", opt, err);
+          return EXIT_FAILURE;
+        }
+
         if (opt == 'i')
           poll_interval = interval;
         else