Bug 819016 - Create some helper functions for reading /sys files. r=bsmedberg

dom/system/gonk/AutoMounter.cpp

@@ -89,48 +89,6 @@ class AutoMounter;
 // try to automount. Any other volumes will be ignored.
 static const nsDependentCString sAutoVolumeName[] = { NS_LITERAL_CSTRING("sdcard") };
 
-/**************************************************************************
-*
-*   Some helper functions for reading/writing files in /sys
-*
-**************************************************************************/
-
-static bool
-ReadSysFile(const char* aFilename, char* aBuf, size_t aBufSize)
-{
-  int fd = open(aFilename, O_RDONLY);
-  if (fd < 0) {
-    ERR("Unable to open file '%s' for reading", aFilename);
-    return false;
-  }
-  ScopedClose autoClose(fd);
-  ssize_t bytesRead = read(fd, aBuf, aBufSize - 1);
-  if (bytesRead < 0) {
-    ERR("Unable to read from file '%s'", aFilename);
-    return false;
-  }
-  if (aBuf[bytesRead - 1] == '\n') {
-    bytesRead--;
-  }
-  aBuf[bytesRead] = '\0';
-  return true;
-}
-
-static bool
-ReadSysFile(const char* aFilename, bool* aVal)
-{
-  char valBuf[20];
-  if (!ReadSysFile(aFilename, valBuf, sizeof(valBuf))) {
-    return false;
-  }
-  int intVal;
-  if (sscanf(valBuf, "%d", &intVal) != 1) {
-    return false;
-  }
-  *aVal = (intVal != 0);
-  return true;
-}
-
 /***************************************************************************/
 
 inline const char* SwitchStateStr(const SwitchEvent& aEvent)
@@ -151,13 +109,18 @@ IsUsbCablePluggedIn()
   // Until then, just go read the file directly
   if (access(ICS_SYS_USB_STATE, F_OK) == 0) {
     char usbState[20];
-    return ReadSysFile(ICS_SYS_USB_STATE,
-                       usbState, sizeof(usbState)) &&
-           (strcmp(usbState, "CONFIGURED") == 0);
+    if (ReadSysFile(ICS_SYS_USB_STATE, usbState, sizeof(usbState))) {
+      return strcmp(usbState, "CONFIGURED") == 0;
+    }
+    ERR("Error reading file '%s': %s", ICS_SYS_USB_STATE, strerror(errno));
+    return false;
   }
   bool configured;
-  return ReadSysFile(GB_SYS_USB_CONFIGURED, &configured) &&
-         configured;
+  if (ReadSysFile(GB_SYS_USB_CONFIGURED, &configured)) {
+    return configured;
+  }
+  ERR("Error reading file '%s': %s", GB_SYS_USB_CONFIGURED, strerror(errno));
+  return false;
 #endif
 }
 
@@ -370,10 +333,17 @@ AutoMounter::UpdateState()
 
   if (access(ICS_SYS_USB_FUNCTIONS, F_OK) == 0) {
     umsAvail = (access(ICS_SYS_UMS_DIRECTORY, F_OK) == 0);
-    char functionsStr[60];
-    umsEnabled = umsAvail &&
-                 ReadSysFile(ICS_SYS_USB_FUNCTIONS, functionsStr, sizeof(functionsStr)) &&
-                 !!strstr(functionsStr, "mass_storage");
+    if (umsAvail) {
+      char functionsStr[60];
+      if (ReadSysFile(ICS_SYS_USB_FUNCTIONS, functionsStr, sizeof(functionsStr))) {
+        umsEnabled = strstr(functionsStr, "mass_storage") != NULL;
+      } else {
+        ERR("Error reading file '%s': %s", ICS_SYS_USB_FUNCTIONS, strerror(errno));
+        umsEnabled = false;
+      }
+    } else {
+      umsEnabled = false;
+    }
   } else {
     umsAvail = ReadSysFile(GB_SYS_UMS_ENABLE, &umsEnabled);
   }

hal/gonk/GonkHal.cpp

@@ -355,43 +355,6 @@ DisableBatteryNotifications()
       NewRunnableFunction(UnregisterBatteryObserverIOThread));
 }
 
-// See bug 819016 about moving the ReadSysFile functions to a
-// central location.
-static bool
-ReadSysFile(const char *aFilename, char *aBuf, size_t aBufSize,
-            size_t *aBytesRead = NULL)
-{
-  int fd = TEMP_FAILURE_RETRY(open(aFilename, O_RDONLY));
-  if (fd < 0) {
-    HAL_LOG(("Unable to open file '%s' for reading", aFilename));
-    return false;
-  }
-  ScopedClose autoClose(fd);
-  ssize_t bytesRead = TEMP_FAILURE_RETRY(read(fd, aBuf, aBufSize - 1));
-  if (bytesRead < 0) {
-    HAL_LOG(("Unable to read from file '%s'", aFilename));
-    return false;
-  }
-  if (bytesRead && (aBuf[bytesRead - 1] == '\n')) {
-    bytesRead--;
-  }
-  aBuf[bytesRead] = '\0';
-  if (aBytesRead) {
-    *aBytesRead = bytesRead;
-  }
-  return true;
-}
-
-static bool
-ReadSysFile(const char *aFilename, int *aVal)
-{
-  char valBuf[20];
-  if (!ReadSysFile(aFilename, valBuf, sizeof(valBuf))) {
-    return false;
-  }
-  return sscanf(valBuf, "%d", aVal) == 1;
-}
-
 static bool
 GetCurrentBatteryCharge(int* aCharge)
 {
@@ -403,7 +366,7 @@ GetCurrentBatteryCharge(int* aCharge)
 
   #ifdef DEBUG
   if ((*aCharge < 0) || (*aCharge > 100)) {
-    HAL_LOG(("charge level containes unknown value: %d", *aCharge));
+    HAL_LOG(("charge level contains unknown value: %d", *aCharge));
   }
   #endif
 
@@ -440,14 +403,12 @@ GetCurrentBatteryCharging(int* aCharging)
   // Otoro device support
 
   char chargingSrcString[16];
-  size_t chargingSrcLen;
 
   success = ReadSysFile("/sys/class/power_supply/battery/status",
-                        chargingSrcString, sizeof(chargingSrcString),
-                        &chargingSrcLen);
+                        chargingSrcString, sizeof(chargingSrcString));
   if (success) {
-    *aCharging = !memcmp(chargingSrcString, "Charging", chargingSrcLen) ||
-                 !memcmp(chargingSrcString, "Full", chargingSrcLen);
+    *aCharging = strcmp(chargingSrcString, "Charging") == 0 ||
+                 strcmp(chargingSrcString, "Full") == 0;
     return true;
   }
 

widget/gonk/nsWindow.cpp

@@ -110,8 +110,8 @@ static const char* kWakeFile = "/sys/power/wait_for_fb_wake";
 
 static void *frameBufferWatcher(void *) {
 
-    int len = 0;
     char buf;
+    bool ret;
 
     nsRefPtr<ScreenOnOffEvent> mScreenOnEvent = new ScreenOnOffEvent(true);
     nsRefPtr<ScreenOnOffEvent> mScreenOffEvent = new ScreenOnOffEvent(false);
@@ -119,23 +119,13 @@ static void *frameBufferWatcher(void *) {
     while (true) {
         // Cannot use epoll here because kSleepFile and kWakeFile are
         // always ready to read and blocking.
-        {
-            ScopedClose fd(open(kSleepFile, O_RDONLY, 0));
-            do {
-                len = read(fd.get(), &buf, 1);
-            } while (len < 0 && errno == EINTR);
-            NS_WARN_IF_FALSE(len >= 0, "WAIT_FOR_FB_SLEEP failed");
-            NS_DispatchToMainThread(mScreenOffEvent);
-        }
+        ret = ReadSysFile(kSleepFile, &buf, sizeof(buf));
+        NS_WARN_IF_FALSE(ret, "WAIT_FOR_FB_SLEEP failed");
+        NS_DispatchToMainThread(mScreenOffEvent);
 
-        {
-            ScopedClose fd(open(kWakeFile, O_RDONLY, 0));
-            do {
-                len = read(fd.get(), &buf, 1);
-            } while (len < 0 && errno == EINTR);
-            NS_WARN_IF_FALSE(len >= 0, "WAIT_FOR_FB_WAKE failed");
-            NS_DispatchToMainThread(mScreenOnEvent);
-        }
+        ret = ReadSysFile(kWakeFile, &buf, sizeof(buf));
+        NS_WARN_IF_FALSE(ret, "WAIT_FOR_FB_WAKE failed");
+        NS_DispatchToMainThread(mScreenOnEvent);
     }
 
     return NULL;

xpcom/glue/FileUtils.cpp

@@ -3,9 +3,13 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#include <errno.h>
+#include <stdio.h>
+
 #include "nscore.h"
 #include "nsStringGlue.h"
 #include "private/pprio.h"
+#include "mozilla/Assertions.h"
 #include "mozilla/FileUtils.h"
 
 #if defined(XP_MACOSX)
@@ -113,6 +117,79 @@ mozilla::fallocate(PRFileDesc *aFD, int64_t aLength)
   return false;
 }
 
+#ifdef MOZ_WIDGET_GONK
+
+#undef TEMP_FAILURE_RETRY
+#define TEMP_FAILURE_RETRY(exp) (__extension__({ \
+  typeof (exp) _rc; \
+  do { \
+    _rc = (exp); \
+  } while (_rc == -1 && errno == EINTR); \
+  _rc; \
+}))
+
+bool
+mozilla::ReadSysFile(
+  const char* aFilename,
+  char* aBuf,
+  size_t aBufSize)
+{
+  int fd = TEMP_FAILURE_RETRY(open(aFilename, O_RDONLY));
+  if (fd < 0) {
+    return false;
+  }
+  ScopedClose autoClose(fd);
+  if (aBufSize == 0) {
+    return true;
+  }
+  ssize_t bytesRead;
+  size_t offset = 0;
+  do {
+    bytesRead = TEMP_FAILURE_RETRY(read(fd, aBuf + offset, aBufSize - offset));
+    if (bytesRead == -1) {
+      return false;
+    }
+    offset += bytesRead;
+  } while (bytesRead > 0 && offset < aBufSize);
+  MOZ_ASSERT(offset <= aBufSize);
+  if (offset > 0 && aBuf[offset - 1] == '\n') {
+    offset--;
+  }
+  if (offset == aBufSize) {
+    MOZ_ASSERT(offset > 0);
+    offset--;
+  }
+  aBuf[offset] = '\0';
+  return true;
+}
+
+bool
+mozilla::ReadSysFile(
+  const char* aFilename,
+  int* aVal)
+{
+  char valBuf[32];
+  if (!ReadSysFile(aFilename, valBuf, sizeof(valBuf))) {
+    return false;
+  }
+  return sscanf(valBuf, "%d", aVal) == 1;
+}
+
+bool
+mozilla::ReadSysFile(
+  const char* aFilename,
+  bool* aVal)
+{
+  int v;
+  if (!ReadSysFile(aFilename, &v)) {
+    return false;
+  }
+  *aVal = (v != 0);
+  return true;
+}
+
+#endif /* MOZ_WIDGET_GONK */
+
 void
 mozilla::ReadAheadLib(nsIFile* aFile)
 {

xpcom/glue/FileUtils.h

@@ -145,5 +145,46 @@ NS_COM_GLUE void ReadAhead(filedesc_t aFd, const size_t aOffset = 0,
                            const size_t aCount = SIZE_MAX);
 
 
+#ifdef MOZ_WIDGET_GONK
+
+/**
+ * Read the contents of a file.
+ * This function is intended for reading a single-lined text files from
+ * /sys/. If the file ends with a newline ('\n') then it will be discarded.
+ * The output buffer will always be '\0'-terminated on successful completion.
+ * If aBufSize == 0, then this function will return true if the file exists
+ * and is readable (it will not attempt to read anything from it).
+ * On failure the contents of aBuf after this call will be undefined and the
+ * value of the global variable errno will be set accordingly.
+ * @return true on success, notice that less than requested bytes could have
+ * been read if the file was smaller
+ */
+bool
+ReadSysFile(
+  const char* aFilename,
+  char* aBuf,
+  size_t aBufSize);
+
+/**
+ * Parse the contents of a file, assuming it contains a decimal integer.
+ * @return true on success
+ */
+bool
+ReadSysFile(
+  const char* aFilename,
+  int* aVal);
+
+/**
+ * Parse the contents of a file, assuming it contains a boolean value
+ * (either 0 or 1).
+ * @return true on success
+ */
+bool
+ReadSysFile(
+  const char* aFilename,
+  bool* aVal);
+
+#endif /* MOZ_WIDGET_GONK */
+
 } // namespace mozilla
 #endif