meminfo: Pull ReadVmallocInfo() out of the SysMemInfo class.

There is no need for the vmalloc reader to be in the sysmeminfo object.
The caller has to create the SysMemInfo object for no reason right now.

Bug: 111694435
Test: libmeminfo_test 1

Change-Id: I263c08c169ea6caf2221bfb915b26ef3c0b1c20c
Signed-off-by: Sandeep Patil <sspatil@google.com>

4 files changed, 49 insertions, 41 deletions

diff --git a/libmeminfo/include/meminfo/sysmeminfo.h b/libmeminfo/include/meminfo/sysmeminfo.h
index 450a46987..83889208d 100644
--- a/libmeminfo/include/meminfo/sysmeminfo.h
+++ b/libmeminfo/include/meminfo/sysmeminfo.h
@@ -58,7 +58,7 @@ class SysMemInfo final {
     // in vmalloc area by the kernel.
     // Note that this deliberately ignores binder buffers. They are _always_
     // mapped in a process and are counted for in each process.
-    uint64_t ReadVmallocInfo(const std::string& path = "/proc/vmallocinfo");
+    uint64_t ReadVmallocInfo();
 
     // getters
     uint64_t mem_total_kb() { return mem_in_kb_[kMemTotal]; }
@@ -84,5 +84,10 @@ class SysMemInfo final {
                      std::function<void(const std::string&, uint64_t)> store_val);
 };
 
+// Parse /proc/vmallocinfo and return total physical memory mapped
+// in vmalloc area by the kernel. Note that this deliberately ignores binder buffers. They are
+// _always_ mapped in a process and are counted for in each process.
+uint64_t ReadVmallocInfo(const std::string& path = "/proc/vmallocinfo");
+
 }  // namespace meminfo
 }  // namespace android
diff --git a/libmeminfo/libmeminfo_benchmark.cpp b/libmeminfo/libmeminfo_benchmark.cpp
index 81fc3b3ad..d88919b66 100644
--- a/libmeminfo/libmeminfo_benchmark.cpp
+++ b/libmeminfo/libmeminfo_benchmark.cpp
@@ -455,8 +455,7 @@ static void BM_VmallocInfo_new(benchmark::State& state) {
     std::string vmallocinfo =
             ::android::base::StringPrintf("%s/testdata1/vmallocinfo", exec_dir.c_str());
     for (auto _ : state) {
-        SysMemInfo smi;
-        CHECK_EQ(smi.ReadVmallocInfo(vmallocinfo), 29884416);
+        CHECK_EQ(::android::meminfo::ReadVmallocInfo(vmallocinfo), 29884416);
     }
 }
 BENCHMARK(BM_VmallocInfo_new);
diff --git a/libmeminfo/libmeminfo_test.cpp b/libmeminfo/libmeminfo_test.cpp
index 7d85dd239..a4db2f25b 100644
--- a/libmeminfo/libmeminfo_test.cpp
+++ b/libmeminfo/libmeminfo_test.cpp
@@ -844,8 +844,7 @@ TEST(SysMemInfoParser, TestVmallocInfoNoMemory) {
     ASSERT_TRUE(::android::base::WriteStringToFd(vmallocinfo, tf.fd));
     std::string file = std::string(tf.path);
 
-    SysMemInfo smi;
-    EXPECT_EQ(smi.ReadVmallocInfo(file), 0);
+    EXPECT_EQ(ReadVmallocInfo(file), 0);
 }
 
 TEST(SysMemInfoParser, TestVmallocInfoKernel) {
@@ -857,8 +856,7 @@ TEST(SysMemInfoParser, TestVmallocInfoKernel) {
     ASSERT_TRUE(::android::base::WriteStringToFd(vmallocinfo, tf.fd));
     std::string file = std::string(tf.path);
 
-    SysMemInfo smi;
-    EXPECT_EQ(smi.ReadVmallocInfo(file), getpagesize());
+    EXPECT_EQ(ReadVmallocInfo(file), getpagesize());
 }
 
 TEST(SysMemInfoParser, TestVmallocInfoModule) {
@@ -870,8 +868,7 @@ TEST(SysMemInfoParser, TestVmallocInfoModule) {
     ASSERT_TRUE(::android::base::WriteStringToFd(vmallocinfo, tf.fd));
     std::string file = std::string(tf.path);
 
-    SysMemInfo smi;
-    EXPECT_EQ(smi.ReadVmallocInfo(file), 6 * getpagesize());
+    EXPECT_EQ(ReadVmallocInfo(file), 6 * getpagesize());
 }
 
 TEST(SysMemInfoParser, TestVmallocInfoAll) {
@@ -888,8 +885,7 @@ TEST(SysMemInfoParser, TestVmallocInfoAll) {
     ASSERT_TRUE(::android::base::WriteStringToFd(vmallocinfo, tf.fd));
     std::string file = std::string(tf.path);
 
-    SysMemInfo smi;
-    EXPECT_EQ(smi.ReadVmallocInfo(file), 7 * getpagesize());
+    EXPECT_EQ(ReadVmallocInfo(file), 7 * getpagesize());
 }
 
 int main(int argc, char** argv) {
diff --git a/libmeminfo/sysmeminfo.cpp b/libmeminfo/sysmeminfo.cpp
index 8fd18d036..5cfa6c373 100644
--- a/libmeminfo/sysmeminfo.cpp
+++ b/libmeminfo/sysmeminfo.cpp
@@ -79,36 +79,8 @@ bool SysMemInfo::ReadMemInfo(const std::vector<std::string>& tags, std::vector<u
     });
 }
 
-uint64_t SysMemInfo::ReadVmallocInfo(const std::string& path) {
-    uint64_t vmalloc_total = 0;
-    auto fp = std::unique_ptr<FILE, decltype(&fclose)>{fopen(path.c_str(), "re"), fclose};
-    if (fp == nullptr) {
-        return vmalloc_total;
-    }
-
-    char line[1024];
-    while (fgets(line, 1024, fp.get()) != nullptr) {
-        // We are looking for lines like
-        // 0x0000000000000000-0x0000000000000000   12288 drm_property_create_blob+0x44/0xec pages=2
-        // vmalloc 0x0000000000000000-0x0000000000000000    8192
-        // wlan_logging_sock_init_svc+0xf8/0x4f0 [wlan] pages=1 vmalloc Notice that if the caller is
-        // coming from a module, the kernel prints and extra "[module_name]" after the address and
-        // the symbol of the call site. This means we can't use the old sscanf() method of getting
-        // the # of pages.
-        char* p_start = strstr(line, "pages=");
-        if (p_start == nullptr) {
-            // we didn't find anything
-            continue;
-        }
-
-        p_start = strtok(p_start, " ");
-        long nr_pages;
-        if (sscanf(p_start, "pages=%ld", &nr_pages) == 1) {
-            vmalloc_total += (nr_pages * getpagesize());
-        }
-    }
-
-    return vmalloc_total;
+uint64_t SysMemInfo::ReadVmallocInfo() {
+    return ::android::meminfo::ReadVmallocInfo();
 }
 
 // TODO: Delete this function if it can't match up with the c-like implementation below.
@@ -263,5 +235,41 @@ bool SysMemInfo::MemZramDevice(const std::string& zram_dev, uint64_t* mem_zram_d
     return false;
 }
 
+// Public methods
+uint64_t ReadVmallocInfo(const std::string& path) {
+    uint64_t vmalloc_total = 0;
+    auto fp = std::unique_ptr<FILE, decltype(&fclose)>{fopen(path.c_str(), "re"), fclose};
+    if (fp == nullptr) {
+        return vmalloc_total;
+    }
+
+    char* line = nullptr;
+    size_t line_alloc = 0;
+    while (getline(&line, &line_alloc, fp.get()) > 0) {
+        // We are looking for lines like
+        //
+        // 0x0000000000000000-0x0000000000000000   12288 drm_property_create_blob+0x44/0xec pages=2 vmalloc
+        // 0x0000000000000000-0x0000000000000000    8192 wlan_logging_sock_init_svc+0xf8/0x4f0 [wlan] pages=1 vmalloc
+        //
+        // Notice that if the caller is coming from a module, the kernel prints and extra
+        // "[module_name]" after the address and the symbol of the call site. This means we can't
+        // use the old sscanf() method of getting the # of pages.
+        char* p_start = strstr(line, "pages=");
+        if (p_start == nullptr) {
+            // we didn't find anything
+            continue;
+        }
+
+        uint64_t nr_pages;
+        if (sscanf(p_start, "pages=%" SCNu64 "", &nr_pages) == 1) {
+            vmalloc_total += (nr_pages * getpagesize());
+        }
+    }
+
+    free(line);
+
+    return vmalloc_total;
+}
+
 }  // namespace meminfo
 }  // namespace android