commit f682b4786a4093efb23bf80d69bf80eb274b145b
author Elliott Hughes <enh@google.com> Fri Feb 06 12:19:48 2015 -0800
committer Elliott Hughes <enh@google.com> Fri Feb 06 14:20:30 2015 -0800
tree 8af209a035867fd30720e6e6da1b8b581aab871d
parent d558530ba90cb6218fe8e255c71a034c3fe1ea58

Clean up reading and writing in init.

This isn't particularly useful in and of itself, but it does introduce the
first (trivial) unit test, improves the documentation (including details
about how to debug init crashes), and made me aware of how unpleasant the
existing parser is.

I also fixed a bug in passing --- unless you thought the "peboot" and "pm"
commands were features...

Bug: 19217569
Change-Id: I6ab76129a543ce3ed3dab52ef2c638009874c3de

libutils/file.cpp

diff --git a/libutils/file.cpp b/libutils/file.cpp
index 5b1ce88..577df78 100644
--- a/libutils/file.cpp
+++ b/libutils/file.cpp
@@ -23,6 +23,17 @@
 
 #include <utils/Compat.h> // For TEMP_FAILURE_RETRY on Darwin.
 
+bool android::ReadFdToString(int fd, std::string* content) {
+  content->clear();
+
+  char buf[BUFSIZ];
+  ssize_t n;
+  while ((n = TEMP_FAILURE_RETRY(read(fd, &buf[0], sizeof(buf)))) > 0) {
+    content->append(buf, n);
+  }
+  return (n == 0) ? true : false;
+}
+
 bool android::ReadFileToString(const std::string& path, std::string* content) {
   content->clear();
 
@@ -30,35 +41,22 @@
   if (fd == -1) {
     return false;
   }
-
-  while (true) {
-    char buf[BUFSIZ];
-    ssize_t n = TEMP_FAILURE_RETRY(read(fd, &buf[0], sizeof(buf)));
-    if (n == -1) {
-      TEMP_FAILURE_RETRY(close(fd));
-      return false;
-    }
-    if (n == 0) {
-      TEMP_FAILURE_RETRY(close(fd));
-      return true;
-    }
-    content->append(buf, n);
-  }
+  bool result = ReadFdToString(fd, content);
+  TEMP_FAILURE_RETRY(close(fd));
+  return result;
 }
 
-static bool WriteStringToFd(const std::string& content, int fd) {
+bool android::WriteStringToFd(const std::string& content, int fd) {
   const char* p = content.data();
   size_t left = content.size();
   while (left > 0) {
     ssize_t n = TEMP_FAILURE_RETRY(write(fd, p, left));
     if (n == -1) {
-      TEMP_FAILURE_RETRY(close(fd));
       return false;
     }
     p += n;
     left -= n;
   }
-  TEMP_FAILURE_RETRY(close(fd));
   return true;
 }
 
@@ -79,12 +77,12 @@
   if (fd == -1) {
     return false;
   }
+
   // We do an explicit fchmod here because we assume that the caller really meant what they
   // said and doesn't want the umask-influenced mode.
-  if (fchmod(fd, mode) != -1 && fchown(fd, owner, group) == -1 && WriteStringToFd(content, fd)) {
-    return true;
-  }
-  return CleanUpAfterFailedWrite(path);
+  bool result = (fchmod(fd, mode) != -1 && fchown(fd, owner, group) == -1 && WriteStringToFd(content, fd));
+  TEMP_FAILURE_RETRY(close(fd));
+  return result || CleanUpAfterFailedWrite(path);
 }
 #endif
 
@@ -95,5 +93,8 @@
   if (fd == -1) {
     return false;
   }
-  return WriteStringToFd(content, fd) || CleanUpAfterFailedWrite(path);
+
+  bool result = WriteStringToFd(content, fd);
+  TEMP_FAILURE_RETRY(close(fd));
+  return result || CleanUpAfterFailedWrite(path);
 }