From 954d6c12f58724773596b1bd669683ce59cae2c5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20G=C3=B6ttsche?= <cgzones@googlemail.com>
Date: Mon, 28 Sep 2020 12:01:56 +0200
Subject: [PATCH] Simplify statm parsing and document unused fields

---
 linux/LinuxProcess.c     |  4 ++--
 linux/LinuxProcessList.c | 31 +++++++++++++------------------
 2 files changed, 15 insertions(+), 20 deletions(-)

diff --git a/linux/LinuxProcess.c b/linux/LinuxProcess.c
index 8fb26e01..373c9ad8 100644
--- a/linux/LinuxProcess.c
+++ b/linux/LinuxProcess.c
@@ -67,8 +67,8 @@ ProcessFieldData Process_fields[] = {
    [M_SHARE] = { .name = "M_SHARE", .title = "  SHR ", .description = "Size of the process's shared pages", .flags = 0, },
    [M_TRS] = { .name = "M_TRS", .title = " CODE ", .description = "Size of the text segment of the process", .flags = 0, },
    [M_DRS] = { .name = "M_DRS", .title = " DATA ", .description = "Size of the data segment plus stack usage of the process", .flags = 0, },
-   [M_LRS] = { .name = "M_LRS", .title = " LIB ", .description = "The library size of the process", .flags = 0, },
-   [M_DT] = { .name = "M_DT", .title = " DIRTY ", .description = "Size of the dirty pages of the process", .flags = 0, },
+   [M_LRS] = { .name = "M_LRS", .title = " LIB ", .description = "The library size of the process (unused since Linux 2.6; always 0)", .flags = 0, },
+   [M_DT] = { .name = "M_DT", .title = " DIRTY ", .description = "Size of the dirty pages of the process (unused since Linux 2.6; always 0)", .flags = 0, },
    [ST_UID] = { .name = "ST_UID", .title = "  UID ", .description = "User ID of the process owner", .flags = 0, },
    [PERCENT_CPU] = { .name = "PERCENT_CPU", .title = "CPU% ", .description = "Percentage of the CPU time the process used in the last sampling", .flags = 0, },
    [PERCENT_MEM] = { .name = "PERCENT_MEM", .title = "MEM% ", .description = "Percentage of the memory the process is using, based on resident memory size", .flags = 0, },
diff --git a/linux/LinuxProcessList.c b/linux/LinuxProcessList.c
index c02bca88..2317e1c8 100644
--- a/linux/LinuxProcessList.c
+++ b/linux/LinuxProcessList.c
@@ -406,25 +406,20 @@ static void LinuxProcessList_readIoFile(LinuxProcess* process, const char* dirna
 
 static bool LinuxProcessList_readStatmFile(LinuxProcess* process, const char* dirname, const char* name) {
    char filename[MAX_NAME+1];
-   xSnprintf(filename, MAX_NAME, "%s/%s/statm", dirname, name);
-   int fd = open(filename, O_RDONLY);
-   if (fd == -1)
+   xSnprintf(filename, sizeof(filename), "%s/%s/statm", dirname, name);
+   FILE* statmfile = fopen(filename, "r");
+   if (!statmfile)
       return false;
-   char buf[PROC_LINE_LENGTH + 1];
-   ssize_t rres = xread(fd, buf, PROC_LINE_LENGTH);
-   close(fd);
-   if (rres < 1) return false;
-
-   char *p = buf;
-   errno = 0;
-   process->super.m_size = strtol(p, &p, 10); if (*p == ' ') p++;
-   process->super.m_resident = strtol(p, &p, 10); if (*p == ' ') p++;
-   process->m_share = strtol(p, &p, 10); if (*p == ' ') p++;
-   process->m_trs = strtol(p, &p, 10); if (*p == ' ') p++;
-   process->m_lrs = strtol(p, &p, 10); if (*p == ' ') p++;
-   process->m_drs = strtol(p, &p, 10); if (*p == ' ') p++;
-   process->m_dt = strtol(p, &p, 10);
-   return (errno == 0);
+   int r = fscanf(statmfile, "%ld %ld %ld %ld %ld %ld %ld",
+                  &process->super.m_size,
+                  &process->super.m_resident,
+                  &process->m_share,
+                  &process->m_trs,
+                  &process->m_lrs,
+                  &process->m_drs,
+                  &process->m_dt);
+   fclose(statmfile);
+   return r == 7;
 }
 
 static bool LinuxProcessList_readSmapsFile(LinuxProcess* process, const char* dirname, const char* name, bool haveSmapsRollup) {