src/tprintf.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * By Daniel Borkmann <daniel@netsniff-ng.org>
   4  * Copyright 2009, 2010 Daniel Borkmann.
   5  * Subject to the GPL.
   6  */
   7
   8 #define _BSD_SOURCE
   9 #include <stdio.h>
  10 #include <stdarg.h>
  11 #include <pthread.h>
  12 #include <assert.h>
  13
  14 #include "tty.h"
  15 #include "tprintf.h"
  16 #include "die.h"
  17
  18 static char buffer[1024];
  19 static size_t buffer_use = 0;
  20 static pthread_spinlock_t buffer_lock;
  21
  22 static size_t lcount = 0;
  23
  24 /*
  25  * We want to print our stuff terminal aligned. Since we're printing packets
  26  * we're in slowpath anyways. If stdin/stdout are connected to a terminal
  27  * then default size = 1024; else size = 4096.
  28  */
  29 void tprintf_flush(void)
  30 {
  31         char *ptr = buffer;
  32         size_t flush_len = get_tty_size() - 5;
  33
  34         while (buffer_use-- > 0) {
  35                 if (lcount == flush_len) {
  36                         fputs("\n   ", stdout);
  37                         lcount = 3;
  38                         while (buffer_use > 0 && (*ptr == ' ' ||
  39                                *ptr == ',' || *ptr == '\n')) {
  40                                 buffer_use--;
  41                                 ptr++;
  42                         }
  43                 }
  44
  45                 if (*ptr == '\n') {
  46                         flush_len = get_tty_size() - 5;
  47                         lcount = -1;
  48                 }
  49
  50                 /* Collect in stream buffer. */
  51                 fputc(*ptr, stdout);
  52                 ptr++;
  53
  54                 lcount++;
  55         }
  56
  57         fflush(stdout);
  58         buffer_use++;
  59         assert(buffer_use == 0);
  60 }
  61
  62 void tprintf_init(void)
  63 {
  64         pthread_spin_init(&buffer_lock, PTHREAD_PROCESS_SHARED);
  65         memset(buffer, 0, sizeof(buffer));
  66 }
  67
  68 void tprintf_cleanup(void)
  69 {
  70         pthread_spin_lock(&buffer_lock);
  71         tprintf_flush();
  72         pthread_spin_unlock(&buffer_lock);
  73         pthread_spin_destroy(&buffer_lock);
  74 }
  75
  76 void tprintf(char *msg, ...)
  77 {
  78         int ret;
  79         va_list vl;
  80
  81         va_start(vl, msg);
  82         pthread_spin_lock(&buffer_lock);
  83
  84         ret = vsnprintf(buffer + buffer_use,
  85                         sizeof(buffer) - buffer_use,
  86                         msg, vl);
  87         if (ret < 0)
  88                 /* Something screwed up! Unexpected. */
  89                 goto out;
  90
  91         if (ret >= sizeof(buffer) - buffer_use) {
  92                 tprintf_flush();
  93
  94                 /* Rewrite the buffer */
  95                 ret = vsnprintf(buffer + buffer_use,
  96                                 sizeof(buffer) - buffer_use,
  97                                 msg, vl);
  98                 /* Again, we've failed! This shouldn't happen! So
  99                  * switch to vfprintf temporarily :-( */
 100                 if (ret >= sizeof(buffer) - buffer_use) {
 101                         fprintf(stderr, "BUG (buffer too large) -->\n");
 102                         vfprintf(stdout, msg, vl);
 103                         fprintf(stderr, " <--\n");
 104                         goto out;
 105                 }
 106         }
 107
 108         if (ret < sizeof(buffer) - buffer_use)
 109                 buffer_use += ret;
 110
 111 out:
 112         pthread_spin_unlock(&buffer_lock);
 113         va_end(vl);
 114 }