Add support for '/proc/[pid]/stat'

Many field values are displayed as 0

src/libos/src/fs/procfs/pid/mod.rs

@@ -8,6 +8,7 @@ use self::cwd::ProcCwdSymINode;
 use self::exe::ProcExeSymINode;
 use self::fd::LockedProcFdDirINode;
 use self::root::ProcRootSymINode;
+use self::stat::ProcStatINode;
 
 mod cmdline;
 mod comm;
@@ -15,6 +16,7 @@ mod cwd;
 mod exe;
 mod fd;
 mod root;
+mod stat;
 
 pub struct LockedPidDirINode(RwLock<PidDirINode>);
 
@@ -58,6 +60,9 @@ impl LockedPidDirINode {
         // comm
         let comm_inode = ProcCommINode::new(&file.process_ref);
         file.entries.insert(String::from("comm"), comm_inode);
+        // stat
+        let stat_inode = ProcStatINode::new(&file.process_ref);
+        file.entries.insert(String::from("stat"), stat_inode);
 
         Ok(())
     }

src/libos/src/fs/procfs/pid/stat.rs

@@ -0,0 +1,185 @@
+use super::*;
+
+pub struct ProcStatINode(ProcessRef);
+
+impl ProcStatINode {
+    pub fn new(process_ref: &ProcessRef) -> Arc<dyn INode> {
+        Arc::new(File::new(Self(Arc::clone(process_ref))))
+    }
+}
+
+impl ProcINode for ProcStatINode {
+    fn generate_data_in_bytes(&self) -> vfs::Result<Vec<u8>> {
+        let main_thread = self.0.main_thread().ok_or(FsError::EntryNotFound)?;
+
+        // Get the process status information, some fields are filled with the
+        // dummy value 0, while some fields are denies to access with value 0.
+        // TODO: Fill in the dummy fields with meaningful values
+        let pid = main_thread.tid();
+        let comm = String::from_utf8(main_thread.name().as_c_str().to_bytes().to_vec()).unwrap();
+        let state = match self.0.status() {
+            ProcessStatus::Running => "R",
+            ProcessStatus::Stopped => "T",
+            ProcessStatus::Zombie => "Z",
+        };
+        let ppid = self.0.parent().pid();
+        let pgrp = self.0.pgid();
+        let session = pgrp.clone();
+        let tty_nr = 0;
+        let tpgid = pgrp.clone();
+        let flags = 0;
+        let minflt = 0;
+        let cminflt = 0;
+        let majflt = 0;
+        let cmajflt = 0;
+        let utime = 0;
+        let stime = 0;
+        let cutime = 0;
+        let cstime = 0;
+        let priority = 0;
+        let nice = 0;
+        let num_threads = self.0.threads().len();
+        let itrealvalue = 0;
+        let starttime = 0;
+        let vsize = main_thread.vm().get_process_range().size();
+        let rss = 0;
+        let rsslim = 0;
+        let startcode = 0;
+        let endcode = 0;
+        let startstack = 0;
+        let kstkesp = 0;
+        let kstkeip = 0;
+        let signal = 0;
+        let blocked = 0;
+        let sigignore = 0;
+        let sigcatch = 0;
+        let wchan = 0;
+        let nswap = 0;
+        let cnswap = 0;
+        let exit_signal = 0;
+        let processor = 0;
+        let rt_priority = 0;
+        let policy = 0;
+        let delayacct_blkio_ticks = 0;
+        let guest_time = 0;
+        let cguest_time = 0;
+        let start_data = 0;
+        let end_data = 0;
+        let start_brk = 0;
+        let arg_start = 0;
+        let arg_end = 0;
+        let env_start = 0;
+        let env_end = 0;
+        let exit_code = 0;
+
+        // Put the information together in the specific format
+        let result = format!(
+            "{} \
+            ({}) \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {} \
+            {}",
+            pid,
+            comm,
+            state,
+            ppid,
+            pgrp,
+            session,
+            tty_nr,
+            tpgid,
+            flags,
+            minflt,
+            cminflt,
+            majflt,
+            cmajflt,
+            utime,
+            stime,
+            cutime,
+            cstime,
+            priority,
+            nice,
+            num_threads,
+            itrealvalue,
+            starttime,
+            vsize,
+            rss,
+            rsslim,
+            startcode,
+            endcode,
+            startstack,
+            kstkesp,
+            kstkeip,
+            signal,
+            blocked,
+            sigignore,
+            sigcatch,
+            wchan,
+            nswap,
+            cnswap,
+            exit_signal,
+            processor,
+            rt_priority,
+            policy,
+            delayacct_blkio_ticks,
+            guest_time,
+            cguest_time,
+            start_data,
+            end_data,
+            start_brk,
+            arg_start,
+            arg_end,
+            env_start,
+            env_end,
+            exit_code
+        )
+        .into_bytes();
+        Ok(result)
+    }
+}

test/procfs/main.c

@@ -29,6 +29,25 @@ static int test_readlink_from_procfs(const char *proc_inode, char *buf, int buf_
     return 0;
 }
 
+static int test_read_from_procfs(const char *proc_inode) {
+    char buf[1024] = { 0 };
+    int len;
+
+    int fd = open(proc_inode, O_RDONLY);
+    if (fd < 0) {
+        THROW_ERROR("failed to open file: %s", proc_inode);
+    }
+    do {
+        len = read(fd, buf, sizeof(buf));
+        if (len < 0) {
+            THROW_ERROR("failed to read: %s", proc_inode);
+        }
+    } while (len == sizeof(buf));
+    close(fd);
+    return 0;
+}
+
+
 // ============================================================================
 // Test cases for procfs
 // ============================================================================
@@ -136,41 +155,45 @@ static int test_read_from_proc_self_comm() {
     return 0;
 }
 
+static int test_read_from_proc_self_stat() {
+    const char *proc_self_stat = "/proc/self/stat";
+    FILE *fp = fopen(proc_self_stat, "r");
+    if (fp == NULL) {
+        THROW_ERROR("failed to fopen: %s", proc_self_stat);
+    }
+
+    int pid, ppid, pgrp;
+    char comm[32] = { 0 };
+    char state[32] = { 0 };
+    int ret = fscanf(fp, "%d %s %s %d %d", &pid, comm, state, &ppid, &pgrp);
+    if (ret != 5) {
+        THROW_ERROR("failed to parse the first 5 items");
+    }
+    if (pid != getpid()) {
+        THROW_ERROR("failed to check the result in %s", proc_self_stat);
+    }
+    printf("cat %s with the first 5 items:\n%d %s %s %d %d\n", proc_self_stat, pid, comm,
+           state, ppid, pgrp);
+
+    fclose(fp);
+    return 0;
+}
+
 static int test_read_from_proc_meminfo() {
-    char meminfo[1024] = { 0 };
     const char *proc_meminfo = "/proc/meminfo";
 
-    int fd = open(proc_meminfo, O_RDONLY);
-    if (fd < 0) {
-        THROW_ERROR("failed to open file: %s", proc_meminfo);
-    }
-    if (read(fd, meminfo, sizeof(meminfo)) < 0) {
+    if (test_read_from_procfs(proc_meminfo) < 0) {
         THROW_ERROR("failed to read the meminfo");
     }
-    close(fd);
-
     return 0;
 }
 
 static int test_read_from_proc_cpuinfo() {
-    char cpuinfo[1024] = { 0 };
     const char *proc_cpuinfo = "/proc/cpuinfo";
-    int len;
 
-    int fd = open(proc_cpuinfo, O_RDONLY);
-    if (fd < 0) {
-        THROW_ERROR("failed to open file: %s", proc_cpuinfo);
+    if (test_read_from_procfs(proc_cpuinfo) < 0) {
+        THROW_ERROR("failed to read the cpuinfo");
     }
-    do {
-        len = read(fd, cpuinfo, sizeof(cpuinfo));
-        if (len < 0) {
-            THROW_ERROR("failed to read the cpuinfo");
-        } else if (len < sizeof(cpuinfo)) {
-            break;
-        }
-    } while (len == sizeof(cpuinfo));
-    close(fd);
-
     return 0;
 }
 
@@ -252,6 +275,7 @@ static test_case_t test_cases[] = {
     TEST_CASE(test_create_and_unlink_file_from_proc_self_root),
     TEST_CASE(test_read_from_proc_self_cmdline),
     TEST_CASE(test_read_from_proc_self_comm),
+    TEST_CASE(test_read_from_proc_self_stat),
     TEST_CASE(test_read_from_proc_meminfo),
     TEST_CASE(test_read_from_proc_cpuinfo),
     TEST_CASE(test_statfs),