Ijar: extract file reading logic to platform_utils

This change takes us closer to compiling ijar,
thus Bazel, with MSVC.

See https://github.com/bazelbuild/bazel/issues/2157
See https://github.com/bazelbuild/bazel/issues/2107

--
MOS_MIGRATED_REVID=140722341

3 files changed, 46 insertions, 40 deletions

diff --git a/third_party/ijar/platform_utils.cc b/third_party/ijar/platform_utils.cc
index a3c4cce82b..1ddfd088a0 100644
--- a/third_party/ijar/platform_utils.cc
+++ b/third_party/ijar/platform_utils.cc
@@ -75,4 +75,42 @@ bool write_file(const char* path, mode_t perm, const void* data, size_t size) {
 #endif  // COMPILER_MSVC
 }
 
+bool read_file(const char* path, void* buffer, size_t size) {
+#ifdef COMPILER_MSVC
+  // TODO(laszlocsomor) 2016-12-01: implement this and other methods, in order
+  // to close https://github.com/bazelbuild/bazel/issues/2157.
+  fprintf(stderr, "Not yet implemented on Windows\n");
+  return false;
+#else   // not COMPILER_MSVC
+  // read the input file
+  int fd = open(path, O_RDONLY);
+  if (fd < 0) {
+    fprintf(stderr, "Can't open file %s for reading: %s\n",
+            path, strerror(errno));
+    return false;
+  }
+  bool result = true;
+  size_t nb_read = 0;
+  while (nb_read < size) {
+    size_t to_read = size - nb_read;
+    if (to_read > 16384 /* 16K */) {
+      to_read = 16384;
+    }
+    ssize_t r = read(fd, static_cast<uint8_t*>(buffer) + nb_read, to_read);
+    if (r < 0) {
+      fprintf(stderr, "Can't read %zu bytes from file %s: %s\n",
+              to_read, path, strerror(errno));
+      result = false;
+      break;
+    }
+    nb_read += r;
+  }
+  if (close(fd)) {
+    fprintf(stderr, "Cannot close file %s: %s\n", path, strerror(errno));
+    result = false;
+  }
+  return result;
+#endif  // COMPILER_MSVC
+}
+
 }  // namespace devtools_ijar
diff --git a/third_party/ijar/platform_utils.h b/third_party/ijar/platform_utils.h
index 9ba9247b2f..65ba902dbf 100644
--- a/third_party/ijar/platform_utils.h
+++ b/third_party/ijar/platform_utils.h
@@ -44,6 +44,11 @@ bool stat_file(const char* path, Stat* result);
 // Returns false upon failure and reports the error to stderr.
 bool write_file(const char* path, mode_t perm, const void* data, size_t size);
 
+// Reads at most `size` bytes into `buffer` from the file under `path`.
+// Returns true upon success: file is opened and all data is read.
+// Returns false upon failure and reports the error to stderr.
+bool read_file(const char* path, void* buffer, size_t size);
+
 }  // namespace devtools_ijar
 
 #endif  // THIRD_PARTY_IJAR_PLATFORM_UTILS_H_
diff --git a/third_party/ijar/zip_main.cc b/third_party/ijar/zip_main.cc
index 4347f018ed..2b99c5f487 100644
--- a/third_party/ijar/zip_main.cc
+++ b/third_party/ijar/zip_main.cc
@@ -21,13 +21,13 @@
 //
 
 #include <errno.h>
-#include <fcntl.h>
 #include <limits.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+
 #include <memory>
 #include <set>
 #include <string>
@@ -158,23 +158,6 @@ void basename(const char *path, char *output, size_t output_size) {
   output[output_size-1] = 0;
 }
 
-// copy size bytes from file descriptor fd into buffer.
-int copy_file_to_buffer(int fd, size_t size, void *buffer) {
-  size_t nb_read = 0;
-  while (nb_read < size) {
-    size_t to_read = size - nb_read;
-    if (to_read > 16384 /* 16K */) {
-      to_read = 16384;
-    }
-    ssize_t r = read(fd, static_cast<uint8_t *>(buffer) + nb_read, to_read);
-    if (r < 0) {
-      return -1;
-    }
-    nb_read += r;
-  }
-  return 0;
-}
-
 // Execute the extraction (or just listing if just v is provided)
 int extract(char *zipfile, char* exdir, char **files, bool verbose,
             bool extract) {
@@ -254,19 +237,9 @@ int add_file(std::unique_ptr<ZipBuilder> const &builder, char *file,
   if (isdir || file_stat.total_size == 0) {
     builder->FinishFile(0);
   } else {
-    // read the input file
-    int fd = open(file, O_RDONLY);
-    if (fd < 0) {
-      fprintf(stderr, "Can't open file %s for reading: %s.\n", file,
-              strerror(errno));
-      return -1;
-    }
-    if (copy_file_to_buffer(fd, file_stat.total_size, buffer) < 0) {
-      fprintf(stderr, "Can't read file %s: %s.\n", file, strerror(errno));
-      close(fd);
+    if (!read_file(file, buffer, file_stat.total_size)) {
       return -1;
     }
-    close(fd);
     builder->FinishFile(file_stat.total_size, compress, true);
   }
   return 0;
@@ -280,20 +253,10 @@ char **read_filelist(char *filename) {
     return NULL;
   }
 
-  int fd = open(filename, O_RDONLY);
-  if (fd < 0) {
-    fprintf(stderr, "Can't open file %s for reading: %s.\n", filename,
-            strerror(errno));
-    return NULL;
-  }
-
   char *data = static_cast<char *>(malloc(file_stat.total_size));
-  if (copy_file_to_buffer(fd, file_stat.total_size, data) < 0) {
-    fprintf(stderr, "Can't read file %s: %s.\n", filename, strerror(errno));
-    close(fd);
+  if (!read_file(filename, data, file_stat.total_size)) {
     return NULL;
   }
-  close(fd);
 
   int nb_entries = 1;
   for (int i = 0; i < file_stat.total_size; i++) {