webpmux: allow reading argument from a file

if a single text file name is supplied as argument
(e.g.: 'webpmux my_long_list_of_frames.txt'), the command
line arguments are actually parsed from this file.
Tokenizer will remove space, tabs, LF, CR, returns, etc.

+ changed ImgIoUtilReadFile() to return a null-terminated
data, for convenience.

+ misc clean-up in the code

BUG=webp:355

Change-Id: I76796305641d660933de5881763d723006712fa9
---

README.mux

@@ -33,6 +33,7 @@ Usage: webpmux -get GET_OPTIONS INPUT -o OUTPUT
        webpmux -info INPUT
        webpmux [-h|-help]
        webpmux -version
+       webpmux argument_file_name
 
 GET_OPTIONS:
  Extract relevant data:
@@ -92,6 +93,9 @@ INPUT & OUTPUT are in WebP format.
 Note: The nature of EXIF, XMP and ICC data is not checked and is assumed to be
 valid.
 
+Note: if a single file name is passed as the argument, the arguments will be
+tokenized from this file. The file name must not start with the character '-'.
+
 Visualization tool:
 ===================
 

examples/webpmux.c

@@ -47,6 +47,7 @@
     webpmux -info in.webp
     webpmux [ -h | -help ]
     webpmux -version
+    webpmux argument_file_name
 */
 
 #ifdef HAVE_CONFIG_H
@@ -108,28 +109,29 @@ static const char* const kDescriptions[LAST_FEATURE] = {
 };
 
 typedef struct {
-  FeatureType type_;
+  // command line arguments
-  FeatureArg* args_;
+  int argc_;
-  int arg_count_;
+  const char** argv_;
-} Feature;
+  WebPData argv_data_;
+  int own_argv_;
 
-typedef struct {
   ActionType action_type_;
   const char* input_;
   const char* output_;
-  Feature feature_;
+  FeatureType type_;
-} WebPMuxConfig;
+  FeatureArg* args_;
+  int arg_count_;
+} Config;
 
 //------------------------------------------------------------------------------
 // Helper functions.
 
-static int CountOccurrences(const char* arglist[], int list_length,
+static int CountOccurrences(const Config* const config, const char* arg) {
-                            const char* arg) {
   int i;
   int num_occurences = 0;
 
-  for (i = 0; i < list_length; ++i) {
+  for (i = 0; i < config->argc_; ++i) {
-    if (!strcmp(arglist[i], arg)) {
+    if (!strcmp(config->argv_[i], arg)) {
       ++num_occurences;
     }
   }
@@ -301,6 +303,7 @@ static void PrintHelp(void) {
   printf("       webpmux -info INPUT\n");
   printf("       webpmux [-h|-help]\n");
   printf("       webpmux -version\n");
+  printf("       webpmux argument_file_name\n");
 
   printf("\n");
   printf("GET_OPTIONS:\n");
@@ -369,6 +372,10 @@ static void PrintHelp(void) {
 
   printf("\nNote: The nature of EXIF, XMP and ICC data is not checked");
   printf(" and is assumed to be\nvalid.\n");
+  printf("\nNote: if a single file name is passed as the argument, the "
+         "arguments will be\n");
+  printf("tokenized from this file. The file name must not start with "
+         "the character '-'.\n");
 }
 
 static void WarnAboutOddOffset(const WebPMuxFrameInfo* const info) {
@@ -394,7 +401,7 @@ static int CreateMux(const char* const filename, WebPMux** mux) {
   assert(mux != NULL);
   if (!ReadFileToWebPData(filename, &bitstream)) return 0;
   *mux = WebPMuxCreate(&bitstream, 1);
-  free((void*)bitstream.bytes);
+  WebPDataClear(&bitstream);
   if (*mux != NULL) return 1;
   fprintf(stderr, "Failed to create mux object from file %s.\n", filename);
   return 0;
@@ -517,10 +524,15 @@ static int ParseBgcolorArgs(const char* args, uint32_t* const bgcolor) {
 //------------------------------------------------------------------------------
 // Clean-up.
 
-static void DeleteConfig(WebPMuxConfig* config) {
+static void DeleteConfig(Config* const config) {
   if (config != NULL) {
-    free(config->feature_.args_);
+    free(config->args_);
+    if (config->own_argv_) {
+      free(config->argv_);
+      WebPDataClear(&config->argv_data_);
+    }
     memset(config, 0, sizeof(*config));
+    WebPDataInit(&config->argv_data_);
   }
 }
 
@@ -531,7 +543,7 @@ static void DeleteConfig(WebPMuxConfig* config) {
 // Returns 1 on valid, 0 otherwise.
 // Also fills up num_feature_args to be number of feature arguments given.
 // (e.g. if there are 4 '-frame's and 1 '-loop', then num_feature_args = 5).
-static int ValidateCommandLine(int argc, const char* argv[],
+static int ValidateCommandLine(const Config* const config,
                                int* num_feature_args) {
   int num_frame_args;
   int num_loop_args;
@@ -543,27 +555,27 @@ static int ValidateCommandLine(int argc, const char* argv[],
   *num_feature_args = 0;
 
   // Simple checks.
-  if (CountOccurrences(argv, argc, "-get") > 1) {
+  if (CountOccurrences(config, "-get") > 1) {
     ERROR_GOTO1("ERROR: Multiple '-get' arguments specified.\n", ErrValidate);
   }
-  if (CountOccurrences(argv, argc, "-set") > 1) {
+  if (CountOccurrences(config, "-set") > 1) {
     ERROR_GOTO1("ERROR: Multiple '-set' arguments specified.\n", ErrValidate);
   }
-  if (CountOccurrences(argv, argc, "-strip") > 1) {
+  if (CountOccurrences(config, "-strip") > 1) {
     ERROR_GOTO1("ERROR: Multiple '-strip' arguments specified.\n", ErrValidate);
   }
-  if (CountOccurrences(argv, argc, "-info") > 1) {
+  if (CountOccurrences(config, "-info") > 1) {
     ERROR_GOTO1("ERROR: Multiple '-info' arguments specified.\n", ErrValidate);
   }
-  if (CountOccurrences(argv, argc, "-o") > 1) {
+  if (CountOccurrences(config, "-o") > 1) {
     ERROR_GOTO1("ERROR: Multiple output files specified.\n", ErrValidate);
   }
 
   // Compound checks.
-  num_frame_args = CountOccurrences(argv, argc, "-frame");
+  num_frame_args = CountOccurrences(config, "-frame");
-  num_loop_args = CountOccurrences(argv, argc, "-loop");
+  num_loop_args = CountOccurrences(config, "-loop");
-  num_bgcolor_args = CountOccurrences(argv, argc, "-bgcolor");
+  num_bgcolor_args = CountOccurrences(config, "-bgcolor");
-  num_durations_args = CountOccurrences(argv, argc, "-duration");
+  num_durations_args = CountOccurrences(config, "-duration");
 
   if (num_loop_args > 1) {
     ERROR_GOTO1("ERROR: Multiple loop counts specified.\n", ErrValidate);
@@ -598,7 +610,7 @@ static int ValidateCommandLine(int argc, const char* argv[],
 
 #define ACTION_IS_NIL (config->action_type_ == NIL_ACTION)
 
-#define FEATURETYPE_IS_NIL (feature->type_ == NIL_FEATURE)
+#define FEATURETYPE_IS_NIL (config->type_ == NIL_FEATURE)
 
 #define CHECK_NUM_ARGS_LESS(NUM, LABEL)                                  \
   if (argc < i + (NUM)) {                                                \
@@ -614,15 +626,15 @@ static int ValidateCommandLine(int argc, const char* argv[],
 
 // Parses command-line arguments to fill up config object. Also performs some
 // semantic checks.
-static int ParseCommandLine(int argc, const char* argv[],
+static int ParseCommandLine(Config* config) {
-                            WebPMuxConfig* config) {
   int i = 0;
   int feature_arg_index = 0;
   int ok = 1;
+  int argc = config->argc_;
+  const char* const* argv = config->argv_;
 
   while (i < argc) {
-    Feature* const feature = &config->feature_;
+    FeatureArg* const arg = &config->args_[feature_arg_index];
-    FeatureArg* const arg = &feature->args_[feature_arg_index];
     if (argv[i][0] == '-') {  // One of the action types or output.
       if (!strcmp(argv[i], "-set")) {
         if (ACTION_IS_NIL) {
@@ -638,8 +650,8 @@ static int ParseCommandLine(int argc, const char* argv[],
         } else {
           ERROR_GOTO1("ERROR: Multiple actions specified.\n", ErrParse);
         }
-        if (FEATURETYPE_IS_NIL || feature->type_ == FEATURE_DURATION) {
+        if (FEATURETYPE_IS_NIL || config->type_ == FEATURE_DURATION) {
-          feature->type_ = FEATURE_DURATION;
+          config->type_ = FEATURE_DURATION;
         } else {
           ERROR_GOTO1("ERROR: Multiple features specified.\n", ErrParse);
         }
@@ -656,7 +668,7 @@ static int ParseCommandLine(int argc, const char* argv[],
       } else if (!strcmp(argv[i], "-strip")) {
         if (ACTION_IS_NIL) {
           config->action_type_ = ACTION_STRIP;
-          feature->arg_count_ = 0;
+          config->arg_count_ = 0;
         } else {
           ERROR_GOTO1("ERROR: Multiple actions specified.\n", ErrParse);
         }
@@ -668,8 +680,8 @@ static int ParseCommandLine(int argc, const char* argv[],
         } else {
           ERROR_GOTO1("ERROR: Multiple actions specified.\n", ErrParse);
         }
-        if (FEATURETYPE_IS_NIL || feature->type_ == FEATURE_ANMF) {
+        if (FEATURETYPE_IS_NIL || config->type_ == FEATURE_ANMF) {
-          feature->type_ = FEATURE_ANMF;
+          config->type_ = FEATURE_ANMF;
         } else {
           ERROR_GOTO1("ERROR: Multiple features specified.\n", ErrParse);
         }
@@ -685,8 +697,8 @@ static int ParseCommandLine(int argc, const char* argv[],
         } else {
           ERROR_GOTO1("ERROR: Multiple actions specified.\n", ErrParse);
         }
-        if (FEATURETYPE_IS_NIL || feature->type_ == FEATURE_ANMF) {
+        if (FEATURETYPE_IS_NIL || config->type_ == FEATURE_ANMF) {
-          feature->type_ = FEATURE_ANMF;
+          config->type_ = FEATURE_ANMF;
         } else {
           ERROR_GOTO1("ERROR: Multiple features specified.\n", ErrParse);
         }
@@ -705,7 +717,7 @@ static int ParseCommandLine(int argc, const char* argv[],
           ERROR_GOTO1("ERROR: Multiple actions specified.\n", ErrParse);
         } else {
           config->action_type_ = ACTION_INFO;
-          feature->arg_count_ = 0;
+          config->arg_count_ = 0;
           config->input_ = argv[i + 1];
         }
         i += 2;
@@ -741,7 +753,7 @@ static int ParseCommandLine(int argc, const char* argv[],
       if (!strcmp(argv[i], "icc") || !strcmp(argv[i], "exif") ||
           !strcmp(argv[i], "xmp")) {
         if (FEATURETYPE_IS_NIL) {
-          feature->type_ = (!strcmp(argv[i], "icc")) ? FEATURE_ICCP :
+          config->type_ = (!strcmp(argv[i], "icc")) ? FEATURE_ICCP :
               (!strcmp(argv[i], "exif")) ? FEATURE_EXIF : FEATURE_XMP;
         } else {
           ERROR_GOTO1("ERROR: Multiple features specified.\n", ErrParse);
@@ -757,7 +769,7 @@ static int ParseCommandLine(int argc, const char* argv[],
       } else if (!strcmp(argv[i], "frame") &&
                  (config->action_type_ == ACTION_GET)) {
         CHECK_NUM_ARGS_LESS(2, ErrParse);
-        feature->type_ = FEATURE_ANMF;
+        config->type_ = FEATURE_ANMF;
         arg->params_ = argv[i + 1];
         ++feature_arg_index;
         i += 2;
@@ -777,9 +789,8 @@ static int ParseCommandLine(int argc, const char* argv[],
 }
 
 // Additional checks after config is filled.
-static int ValidateConfig(WebPMuxConfig* config) {
+static int ValidateConfig(Config* const config) {
   int ok = 1;
-  Feature* const feature = &config->feature_;
 
   // Action.
   if (ACTION_IS_NIL) {
@@ -795,7 +806,7 @@ static int ValidateConfig(WebPMuxConfig* config) {
   if (config->input_ == NULL) {
     if (config->action_type_ != ACTION_SET) {
       ERROR_GOTO1("ERROR: No input file specified.\n", ErrValidate2);
-    } else if (feature->type_ != FEATURE_ANMF) {
+    } else if (config->type_ != FEATURE_ANMF) {
       ERROR_GOTO1("ERROR: No input file specified.\n", ErrValidate2);
     }
   }
@@ -809,29 +820,63 @@ static int ValidateConfig(WebPMuxConfig* config) {
   return ok;
 }
 
-// Create config object from command-line arguments.
+#define MAX_ARGC 16384
-static int InitializeConfig(int argc, const char* argv[],
+static int SetArguments(int argc, const char* argv[],
-                            WebPMuxConfig* config) {
+                        Config* const config) {
-  int num_feature_args = 0;
-  int ok = 1;
-
   assert(config != NULL);
   memset(config, 0, sizeof(*config));
+  WebPDataInit(&config->argv_data_);
+  if (argc == 1 && argv[0][0] != '-') {
+    char* cur;
+    const char sep[] = " \t\r\n\f\v";
+    if (!ReadFileToWebPData(argv[0], &config->argv_data_)) {
+      return 0;
+    }
+    config->own_argv_ = 1;
+    config->argv_ = (const char**)malloc(MAX_ARGC * sizeof(*config->argv_));
+    if (config->argv_ == NULL) return 0;
+
+    argc = 0;
+    for (cur = strtok((char*)config->argv_data_.bytes, sep);
+         cur != NULL;
+         cur = strtok(NULL, sep)) {
+      if (argc == MAX_ARGC) {
+        fprintf(stderr, "ERROR: Arguments limit %d reached\n", MAX_ARGC);
+        return 0;
+      }
+      assert(strlen(cur) != 0);
+      config->argv_[argc++] = cur;
+    }
+    config->argc_ = argc;
+  } else {
+    config->argc_ = argc;
+    config->argv_ = argv;
+    config->own_argv_ = 0;
+  }
+  return 1;
+}
+
+// Create config object from command-line arguments.
+static int InitializeConfig(int argc, const char* argv[],
+                            Config* const config) {
+  int num_feature_args = 0;
+  int ok = SetArguments(argc, argv, config);
+
+  if (!ok) return 0;
 
   // Validate command-line arguments.
-  if (!ValidateCommandLine(argc, argv, &num_feature_args)) {
+  if (!ValidateCommandLine(config, &num_feature_args)) {
     ERROR_GOTO1("Exiting due to command-line parsing error.\n", Err1);
   }
 
-  config->feature_.arg_count_ = num_feature_args;
+  config->arg_count_ = num_feature_args;
-  config->feature_.args_ =
+  config->args_ = (FeatureArg*)calloc(num_feature_args, sizeof(*config->args_));
-      (FeatureArg*)calloc(num_feature_args, sizeof(*config->feature_.args_));
+  if (config->args_ == NULL) {
-  if (config->feature_.args_ == NULL) {
     ERROR_GOTO1("ERROR: Memory allocation error.\n", Err1);
   }
 
   // Parse command-line.
-  if (!ParseCommandLine(argc, argv, config) || !ValidateConfig(config)) {
+  if (!ParseCommandLine(config) || !ValidateConfig(config)) {
     ERROR_GOTO1("Exiting due to command-line parsing error.\n", Err1);
   }
 
@@ -847,7 +892,7 @@ static int InitializeConfig(int argc, const char* argv[],
 //------------------------------------------------------------------------------
 // Processing.
 
-static int GetFrame(const WebPMux* mux, const WebPMuxConfig* config) {
+static int GetFrame(const WebPMux* mux, const Config* config) {
   WebPMuxError err = WEBP_MUX_OK;
   WebPMux* mux_single = NULL;
   int num = 0;
@@ -857,7 +902,7 @@ static int GetFrame(const WebPMux* mux, const WebPMuxConfig* config) {
   WebPMuxFrameInfo info;
   WebPDataInit(&info.bitstream);
 
-  num = ExUtilGetInt(config->feature_.args_[0].params_, 10, &parse_error);
+  num = ExUtilGetInt(config->args_[0].params_, 10, &parse_error);
   if (num < 0) {
     ERROR_GOTO1("ERROR: Frame/Fragment index must be non-negative.\n", ErrGet);
   }
@@ -891,18 +936,17 @@ static int GetFrame(const WebPMux* mux, const WebPMuxConfig* config) {
 }
 
 // Read and process config.
-static int Process(const WebPMuxConfig* config) {
+static int Process(const Config* config) {
   WebPMux* mux = NULL;
   WebPData chunk;
   WebPMuxError err = WEBP_MUX_OK;
   int ok = 1;
-  const Feature* const feature = &config->feature_;
 
   switch (config->action_type_) {
     case ACTION_GET: {
       ok = CreateMux(config->input_, &mux);
       if (!ok) goto Err2;
-      switch (feature->type_) {
+      switch (config->type_) {
         case FEATURE_ANMF:
           ok = GetFrame(mux, config);
           break;
@@ -910,10 +954,10 @@ static int Process(const WebPMuxConfig* config) {
         case FEATURE_ICCP:
         case FEATURE_EXIF:
         case FEATURE_XMP:
-          err = WebPMuxGetChunk(mux, kFourccList[feature->type_], &chunk);
+          err = WebPMuxGetChunk(mux, kFourccList[config->type_], &chunk);
           if (err != WEBP_MUX_OK) {
             ERROR_GOTO3("ERROR (%s): Could not get the %s.\n",
-                        ErrorString(err), kDescriptions[feature->type_], Err2);
+                        ErrorString(err), kDescriptions[config->type_], Err2);
           }
           ok = WriteData(config->output_, &chunk);
           break;
@@ -925,7 +969,7 @@ static int Process(const WebPMuxConfig* config) {
       break;
     }
     case ACTION_SET: {
-      switch (feature->type_) {
+      switch (config->type_) {
         case FEATURE_ANMF: {
           int i;
           WebPMuxAnimParams params = { 0xFFFFFFFF, 0 };
@@ -934,11 +978,11 @@ static int Process(const WebPMuxConfig* config) {
             ERROR_GOTO2("ERROR (%s): Could not allocate a mux object.\n",
                         ErrorString(WEBP_MUX_MEMORY_ERROR), Err2);
           }
-          for (i = 0; i < feature->arg_count_; ++i) {
+          for (i = 0; i < config->arg_count_; ++i) {
-            switch (feature->args_[i].subtype_) {
+            switch (config->args_[i].subtype_) {
               case SUBTYPE_BGCOLOR: {
                 uint32_t bgcolor;
-                ok = ParseBgcolorArgs(feature->args_[i].params_, &bgcolor);
+                ok = ParseBgcolorArgs(config->args_[i].params_, &bgcolor);
                 if (!ok) {
                   ERROR_GOTO1("ERROR: Could not parse the background color \n",
                               Err2);
@@ -949,7 +993,7 @@ static int Process(const WebPMuxConfig* config) {
               case SUBTYPE_LOOP: {
                 int parse_error = 0;
                 const int loop_count =
-                    ExUtilGetInt(feature->args_[i].params_, 10, &parse_error);
+                    ExUtilGetInt(config->args_[i].params_, 10, &parse_error);
                 if (loop_count < 0 || loop_count > 65535) {
                   // Note: This is only a 'necessary' condition for loop_count
                   // to be valid. The 'sufficient' conditioned in checked in
@@ -965,10 +1009,10 @@ static int Process(const WebPMuxConfig* config) {
               case SUBTYPE_ANMF: {
                 WebPMuxFrameInfo frame;
                 frame.id = WEBP_CHUNK_ANMF;
-                ok = ReadFileToWebPData(feature->args_[i].filename_,
+                ok = ReadFileToWebPData(config->args_[i].filename_,
                                         &frame.bitstream);
                 if (!ok) goto Err2;
-                ok = ParseFrameArgs(feature->args_[i].params_, &frame);
+                ok = ParseFrameArgs(config->args_[i].params_, &frame);
                 if (!ok) {
                   WebPDataClear(&frame.bitstream);
                   ERROR_GOTO1("ERROR: Could not parse frame properties.\n",
@@ -1001,13 +1045,13 @@ static int Process(const WebPMuxConfig* config) {
         case FEATURE_XMP: {
           ok = CreateMux(config->input_, &mux);
           if (!ok) goto Err2;
-          ok = ReadFileToWebPData(feature->args_[0].filename_, &chunk);
+          ok = ReadFileToWebPData(config->args_[0].filename_, &chunk);
           if (!ok) goto Err2;
-          err = WebPMuxSetChunk(mux, kFourccList[feature->type_], &chunk, 1);
+          err = WebPMuxSetChunk(mux, kFourccList[config->type_], &chunk, 1);
           free((void*)chunk.bytes);
           if (err != WEBP_MUX_OK) {
             ERROR_GOTO3("ERROR (%s): Could not set the %s.\n",
-                        ErrorString(err), kDescriptions[feature->type_], Err2);
+                        ErrorString(err), kDescriptions[config->type_], Err2);
           }
           break;
         }
@@ -1043,11 +1087,11 @@ static int Process(const WebPMuxConfig* config) {
         for (i = 0; i < num_frames; ++i) durations[i] = -1;
 
         // Parse intervals to process.
-        for (i = 0; i < feature->arg_count_; ++i) {
+        for (i = 0; i < config->arg_count_; ++i) {
           int k;
           int args[3];
           int duration, start, end;
-          const int nb_args = ExUtilGetInts(feature->args_[i].params_,
+          const int nb_args = ExUtilGetInts(config->args_[i].params_,
                                             10, 3, args);
           ok = (nb_args >= 1);
           if (!ok) goto Err3;
@@ -1105,12 +1149,12 @@ static int Process(const WebPMuxConfig* config) {
     case ACTION_STRIP: {
       ok = CreateMux(config->input_, &mux);
       if (!ok) goto Err2;
-      if (feature->type_ == FEATURE_ICCP || feature->type_ == FEATURE_EXIF ||
+      if (config->type_ == FEATURE_ICCP || config->type_ == FEATURE_EXIF ||
-          feature->type_ == FEATURE_XMP) {
+          config->type_ == FEATURE_XMP) {
-        err = WebPMuxDeleteChunk(mux, kFourccList[feature->type_]);
+        err = WebPMuxDeleteChunk(mux, kFourccList[config->type_]);
         if (err != WEBP_MUX_OK) {
           ERROR_GOTO3("ERROR (%s): Could not strip the %s.\n",
-                      ErrorString(err), kDescriptions[feature->type_], Err2);
+                      ErrorString(err), kDescriptions[config->type_], Err2);
         }
       } else {
         ERROR_GOTO1("ERROR: Invalid feature for action 'strip'.\n", Err2);
@@ -1140,7 +1184,7 @@ static int Process(const WebPMuxConfig* config) {
 // Main.
 
 int main(int argc, const char* argv[]) {
-  WebPMuxConfig config;
+  Config config;
   int ok = InitializeConfig(argc - 1, argv + 1, &config);
   if (ok) {
     ok = Process(&config);

imageio/imageio_util.c

@@ -47,7 +47,8 @@ int ImgIoUtilReadFromStdin(const uint8_t** data, size_t* data_size) {
   while (!feof(stdin)) {
     // We double the buffer size each time and read as much as possible.
     const size_t extra_size = (max_size == 0) ? kBlockSize : max_size;
-    void* const new_data = realloc(input, max_size + extra_size);
+    // we allocate one extra byte for the \0 terminator
+    void* const new_data = realloc(input, max_size + extra_size + 1);
     if (new_data == NULL) goto Error;
     input = (uint8_t*)new_data;
     max_size += extra_size;
@@ -55,6 +56,7 @@ int ImgIoUtilReadFromStdin(const uint8_t** data, size_t* data_size) {
     if (size < max_size) break;
   }
   if (ferror(stdin)) goto Error;
+  if (input != NULL) input[size] = '\0';  // convenient 0-terminator
   *data = input;
   *data_size = size;
   return 1;
@@ -68,7 +70,7 @@ int ImgIoUtilReadFromStdin(const uint8_t** data, size_t* data_size) {
 int ImgIoUtilReadFile(const char* const file_name,
                       const uint8_t** data, size_t* data_size) {
   int ok;
-  void* file_data;
+  uint8_t* file_data;
   size_t file_size;
   FILE* in;
   const int from_stdin = (file_name == NULL) || !strcmp(file_name, "-");
@@ -87,7 +89,8 @@ int ImgIoUtilReadFile(const char* const file_name,
   fseek(in, 0, SEEK_END);
   file_size = ftell(in);
   fseek(in, 0, SEEK_SET);
-  file_data = malloc(file_size);
+  // we allocate one extra byte for the \0 terminator
+  file_data = (uint8_t*)malloc(file_size + 1);
   if (file_data == NULL) {
     fclose(in);
     fprintf(stderr, "memory allocation failure when reading file %s\n",
@@ -103,11 +106,14 @@ int ImgIoUtilReadFile(const char* const file_name,
     free(file_data);
     return 0;
   }
-  *data = (uint8_t*)file_data;
+  file_data[file_size] = '\0';  // convenient 0-terminator
+  *data = file_data;
   *data_size = file_size;
   return 1;
 }
 
+// -----------------------------------------------------------------------------
+
 int ImgIoUtilWriteFile(const char* const file_name,
                        const uint8_t* data, size_t data_size) {
   int ok;

imageio/imageio_util.h

@@ -30,6 +30,9 @@ FILE* ImgIoUtilSetBinaryMode(FILE* file);
 // Allocates storage for entire file 'file_name' and returns contents and size
 // in 'data' and 'data_size'. Returns 1 on success, 0 otherwise. '*data' should
 // be deleted using free().
+// Note: for convenience, the data will be null-terminated with an extra byte
+// (not accounted for in *data_size), in case the file is text and intended
+// to be used as a C-string.
 // If 'file_name' is NULL or equal to "-", input is read from stdin by calling
 // the function ImgIoUtilReadFromStdin().
 int ImgIoUtilReadFile(const char* const file_name,

man/webpmux.1

@@ -1,5 +1,5 @@
 .\"                                      Hey, EMACS: -*- nroff -*-
-.TH WEBPMUX 1 "November 10, 2016"
+.TH WEBPMUX 1 "December 1, 2017"
 .SH NAME
 webpmux \- create animated WebP files from non\-animated WebP images, extract
 frames from animated WebP images, and manage XMP/EXIF metadata and ICC profile.
@@ -48,6 +48,8 @@ frames from animated WebP images, and manage XMP/EXIF metadata and ICC profile.
 .B webpmux [\-h|\-help]
 .br
 .B webpmux \-version
+.br
+.B webpmux argument_file_name
 .SH DESCRIPTION
 This manual page documents the
 .B webpmux
@@ -55,6 +57,9 @@ command.
 .PP
 \fBwebpmux\fP can be used to create/extract from animated WebP files, as well as
 to add/extract/strip XMP/EXIF metadata and ICC profile.
+If a single file name (not starting with the character '\-') is supplied as
+the argument, the command line argument are actually tokenized from this file.
+This allows for easy scripting or using large number of arguments.
 .SH OPTIONS
 .SS GET_OPTIONS (\-get):
 .TP