lib: process-stat - Use buffer_append_full_istream() to read files

diff --git a/src/lib/process-stat.c b/src/lib/process-stat.c
index 782503e60bae77ae87e6a61d228c2fc1887e328c..60eddbc3ecb62acc6abd334fc232f7c5d3244f9a 100644 (file)
--- a/src/lib/process-stat.c
+++ b/src/lib/process-stat.c
@@ -1,6 +1,9 @@
 /* Copyright (c) 2008-2021 Dovecot authors, see the included COPYING file */
 
 #include "lib.h"
+#include "buffer.h"
+#include "str.h"
+#include "istream.h"
 #include "process-stat.h"
 #include "time-util.h"
 #include <limits.h>
@@ -12,8 +15,12 @@
 #include <stdio.h>
 
 #define PROC_STAT_PATH "/proc/self/stat"
+#define PROC_STAT_MAX_SIZE 1024
 #define PROC_STATUS_PATH "/proc/self/status"
+#define PROC_STATUS_MAX_SIZE 2048
 #define PROC_IO_PATH "/proc/self/io"
+#define PROC_IO_MAX_SIZE 1024
+#define PROC_BUFFER_INITIAL_SIZE 512
 
 static const uint64_t stat_undefined = 0xFFFFFFFFFFFFFFFF;
 
@@ -71,39 +78,38 @@ static int open_fd(const char *path, struct event *event)
 }
 
 static int
-read_file(int fd, const char *path, char *buf_r, size_t buf_size, struct event *event)
+read_file_buffer(const char *path, string_t *buf, size_t max_size, struct event *event)
 {
-       ssize_t ret;
-       ret = read(fd, buf_r, buf_size);
-       if (ret <= 0) {
-               if (ret == -1)
-                       e_error(event, "read(%s) failed: %m", path);
-               else
-                       e_error(event, "read(%s) returned EOF", path);
-       } else if (ret == (ssize_t)buf_size) {
-               e_error(event, "%s is larger than expected", path);
-               buf_r[buf_size - 1] = '\0';
-       } else {
-               buf_r[ret] = '\0';
+       const char *error;
+       int fd = open_fd(path, event);
+       if (fd < 0)
+               return -1;
+       struct istream *is = i_stream_create_fd_autoclose(&fd, max_size);
+       i_stream_set_name(is, path);
+       enum buffer_append_result res =
+               buffer_append_full_istream(buf, is, max_size, &error);
+       i_stream_unref(&is);
+       if (res == BUFFER_APPEND_READ_MAX_SIZE)
+               e_error(event, "%s is larger than expected (%zu)", path, max_size);
+       else if (res != BUFFER_APPEND_OK) {
+               e_error(event, "read(%s) failed: %s", path, error);
+               return -1;
        }
-       i_close_fd(&fd);
-       return ret <= 0 ? -1 : 0;
+       return 0;
 }
 
 static int parse_key_val_file(const char *path,
+                             size_t max_size,
                              struct key_val *fields,
                              struct event *event)
 {
-       char buf[2048];
-       int fd;
-
-       fd = open_fd(path, event);
-       if (fd == -1 || read_file(fd, path, buf, sizeof(buf), event) < 0) {
+       string_t *buf = t_str_new(PROC_BUFFER_INITIAL_SIZE);
+       if (read_file_buffer(path, buf, max_size, event) < 0) {
                for (; fields->key != NULL; fields++)
                        *fields->value = stat_undefined;
                return -1;
        }
-       buffer_parse(buf, fields);
+       buffer_parse(str_c(buf), fields);
        return 0;
 }
 
@@ -117,7 +123,8 @@ static int parse_proc_io(struct process_stat *stat_r, struct event *event)
                { NULL, NULL, 0 },
        };
        if (stat_r->proc_io_failed ||
-           parse_key_val_file(PROC_IO_PATH, fields, event) < 0) {
+           parse_key_val_file(PROC_IO_PATH, PROC_IO_MAX_SIZE, fields,
+                              event) < 0) {
                stat_r->proc_io_failed = TRUE;
                return -1;
        }
@@ -132,7 +139,8 @@ static int parse_proc_status(struct process_stat *stat_r, struct event *event)
                { NULL, NULL, 0 },
        };
        if (stat_r->proc_status_failed ||
-           parse_key_val_file(PROC_STATUS_PATH, fields, event) < 0) {
+           parse_key_val_file(PROC_STATUS_PATH, PROC_STATUS_MAX_SIZE,
+                              fields, event) < 0) {
                stat_r->proc_status_failed = TRUE;
                return -1;
        }
@@ -156,8 +164,7 @@ static int stat_get_rusage(struct process_stat *stat_r)
 
 static int parse_stat_file(struct process_stat *stat_r, struct event *event)
 {
-       int fd = -1;
-       char buf[1024];
+       string_t *buf = t_str_new(PROC_BUFFER_INITIAL_SIZE);
        unsigned int i;
        const char *const *tmp;
        struct {
@@ -171,9 +178,8 @@ static int parse_stat_file(struct process_stat *stat_r, struct event *event)
                { &stat_r->vsz, 22 },
                { &stat_r->rss, 23 },
        };
-       if (!stat_r->proc_stat_failed)
-               fd = open_fd(PROC_STAT_PATH, event);
-       if (fd == -1) {
+       if (stat_r->proc_stat_failed ||
+           read_file_buffer(PROC_STAT_PATH, buf, PROC_STAT_MAX_SIZE, event) < 0) {
                stat_r->proc_stat_failed = TRUE;
                /* vsz and rss are not provided by getrusage(), setting to undefined */
                stat_r->vsz = stat_undefined;
@@ -187,11 +193,7 @@ static int parse_stat_file(struct process_stat *stat_r, struct event *event)
                }
                return 0;
        }
-       if (read_file(fd, PROC_STAT_PATH, buf, sizeof(buf), event) < 0) {
-               stat_r->proc_stat_failed = TRUE;
-               return -1;
-       }
-       tmp = t_strsplit(buf, " ");
+       tmp = t_strsplit(str_c(buf), " ");
        unsigned int tmp_count = str_array_length(tmp);
 
        for (i = 0; i < N_ELEMENTS(fields); i++) {
@@ -208,13 +210,15 @@ static int parse_all_stats(struct process_stat *stat_r, struct event *event)
 {
        bool has_fields = FALSE;
 
-       if (parse_stat_file(stat_r, event) == 0)
-               has_fields = TRUE;
-       if (parse_proc_io(stat_r, event) == 0)
-               has_fields = TRUE;
-       if ((!stat_r->proc_stat_failed || stat_r->rusage_failed) &&
-           parse_proc_status(stat_r, event) == 0)
-               has_fields = TRUE;
+       T_BEGIN {
+               if (parse_stat_file(stat_r, event) == 0)
+                       has_fields = TRUE;
+               if (parse_proc_io(stat_r, event) == 0)
+                       has_fields = TRUE;
+               if ((!stat_r->proc_stat_failed || stat_r->rusage_failed) &&
+                   parse_proc_status(stat_r, event) == 0)
+                       has_fields = TRUE;
+       } T_END;
 
        if (has_fields)
                return 0;