Backed out changeset d89a7ed61c19 (bug 1035396) for asan failures

xpcom/base/nsMemoryReporterManager.cpp

@@ -45,9 +45,6 @@ using namespace mozilla;
 
 #if defined(XP_LINUX)
 
-#include <string.h>
-#include <stdlib.h>
-
 static nsresult
 GetProcSelfStatmField(int aField, int64_t* aN)
 {
@@ -71,48 +68,30 @@ GetProcSelfStatmField(int aField, int64_t* aN)
 static nsresult
 GetProcSelfSmapsPrivate(int64_t* aN)
 {
-  // You might be tempted to calculate USS by subtracting the "shared" value
-  // from the "resident" value in /proc/<pid>/statm. But at least on Linux,
-  // statm's "shared" value actually counts pages backed by files, which has
-  // little to do with whether the pages are actually shared. /proc/self/smaps
-  // on the other hand appears to give us the correct information.
+  // You might be tempted to calculate USS by subtracting the "shared"
+  // value from the "resident" value in /proc/<pid>/statm. But at least
+  // on Linux, statm's "shared" value actually counts pages backed by
+  // files, which has little to do with whether the pages are actually
+  // shared. /proc/self/smaps on the other hand appears to give us the
+  // correct information.
 
   FILE* f = fopen("/proc/self/smaps", "r");
   if (NS_WARN_IF(!f)) {
     return NS_ERROR_UNEXPECTED;
   }
 
-  // We carry over the end of the buffer to make sure we don't accidentally
-  // break on an interesting line.
-  static const uint32_t carryOver = 32;
-  static const uint32_t readSize = 4096;
-
   int64_t amount = 0;
-  char buffer[carryOver + readSize + 1];
-  memset(buffer, ' ', carryOver);
-
-  for (;;) {
-    size_t bytes = fread(buffer + carryOver, sizeof(*buffer), readSize, f);
-    char* end = buffer + bytes;
-    char* ptr = buffer;
-    end[carryOver] = '\0';
-    // We are looking for lines like "Private_{Clean,Dirty}: 4 kB".
-    while (ptr = strstr(ptr, "Private")) {
-      ptr += sizeof("Private_Xxxxx:");
-      amount += atoi(ptr);
-      if (ptr >= end) {
-        break;
-      }
+  char line[256];
+  while (fgets(line, sizeof(line), f)) {
+    long long val = 0;
+    if (sscanf(line, "Private_Dirty: %lld kB", &val) == 1 ||
+        sscanf(line, "Private_Clean: %lld kB", &val) == 1) {
+      amount += val * 1024; // convert from kB to bytes
     }
-    if (bytes < readSize) {
-      break;
-    }
-    memcpy(buffer, end, carryOver);
   }
 
   fclose(f);
-  // Convert from kB to bytes.
-  *aN = amount * 1024;
+  *aN = amount;
   return NS_OK;
 }