FFmpeg
ffeval.c
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1 /*
2  * Copyright (c) 2012 Stefano Sabatini
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "config.h"
22 #if HAVE_UNISTD_H
23 #include <unistd.h> /* getopt */
24 #endif
25 
26 #include "libavutil/eval.h"
27 #include "libavutil/mem.h"
28 
29 #if !HAVE_GETOPT
30 #include "compat/getopt.c"
31 #endif
32 
33 /**
34  * @file
35  * simple arithmetic expression evaluator
36  */
37 
38 static void usage(void)
39 {
40  printf("Simple expression evalutor, please *don't* turn me to a feature-complete language interpreter\n");
41  printf("usage: ffeval [OPTIONS]\n");
42  printf("\n"
43  "Options:\n"
44  "-e echo each input line on output\n"
45  "-h print this help\n"
46  "-i INFILE set INFILE as input file, stdin if omitted\n"
47  "-o OUTFILE set OUTFILE as output file, stdout if omitted\n"
48  "-p PROMPT set output prompt\n");
49 }
50 
51 int main(int argc, char **argv)
52 {
53  int buf_size = 0;
54  char *buf = NULL;
55  const char *outfilename = NULL, *infilename = NULL;
56  FILE *outfile = NULL, *infile = NULL;
57  const char *prompt = "=> ";
58  int count = 0, echo = 0;
59  int c;
60 
61 #define GROW_ARRAY() \
62  do { \
63  if (!av_dynarray2_add((void **)&buf, &buf_size, 1, NULL)) { \
64  av_log(NULL, AV_LOG_ERROR, \
65  "Memory allocation problem occurred\n"); \
66  return 1; \
67  } \
68  } while (0)
69 
70  GROW_ARRAY();
71  while ((c = getopt(argc, argv, "ehi:o:p:")) != -1) {
72  switch (c) {
73  case 'e':
74  echo = 1;
75  break;
76  case 'h':
77  usage();
78  return 0;
79  case 'i':
80  infilename = optarg;
81  break;
82  case 'o':
83  outfilename = optarg;
84  break;
85  case 'p':
86  prompt = optarg;
87  break;
88  case '?':
89  return 1;
90  }
91  }
92 
93  if (!infilename || !strcmp(infilename, "-")) {
94  infilename = "stdin";
95  infile = stdin;
96  } else {
97  infile = fopen(infilename, "r");
98  }
99  if (!infile) {
100  fprintf(stderr, "Impossible to open input file '%s': %s\n", infilename, strerror(errno));
101  return 1;
102  }
103 
104  if (!outfilename || !strcmp(outfilename, "-")) {
105  outfilename = "stdout";
106  outfile = stdout;
107  } else {
108  outfile = fopen(outfilename, "w");
109  }
110  if (!outfile) {
111  fprintf(stderr, "Impossible to open output file '%s': %s\n", outfilename, strerror(errno));
112  return 1;
113  }
114 
115  while ((c = fgetc(infile)) != EOF) {
116  if (c == '\n') {
117  double d;
118 
119  buf[count] = 0;
120  if (buf[0] != '#') {
121  int ret = av_expr_parse_and_eval(&d, buf,
122  NULL, NULL,
123  NULL, NULL, NULL, NULL, NULL, 0, NULL);
124  if (echo)
125  fprintf(outfile, "%s ", buf);
126  if (ret >= 0) fprintf(outfile, "%s%f\n", prompt, d);
127  else fprintf(outfile, "%s%f (%s)\n", prompt, d, av_err2str(ret));
128  }
129  count = 0;
130  } else {
131  if (count >= buf_size-1)
132  GROW_ARRAY();
133  buf[count++] = c;
134  }
135  }
136 
137  av_free(buf);
138  return 0;
139 }
#define NULL
Definition: coverity.c:32
Memory handling functions.
static void usage(void)
Definition: ffeval.c:38
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
int av_expr_parse_and_eval(double *d, const char *s, const char *const *const_names, const double *const_values, const char *const *func1_names, double(*const *funcs1)(void *, double), const char *const *func2_names, double(*const *funcs2)(void *, double, double), void *opaque, int log_offset, void *log_ctx)
Parse and evaluate an expression.
Definition: eval.c:776
GLsizei count
Definition: opengl_enc.c:108
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: error.h:119
#define GROW_ARRAY()
static int getopt(int argc, char *argv[], char *opts)
Definition: getopt.c:41
void * buf
Definition: avisynth_c.h:766
static char * optarg
Definition: getopt.c:39
#define av_free(p)
printf("static const uint8_t my_array[100] = {\n")
int main(int argc, char **argv)
Definition: ffeval.c:51
FILE * outfile
Definition: audiogen.c:96
simple arithmetic expression evaluator