Merge pull request #49 from hallyn/offset1

fix corner cases in uptime and diskstat read

diff --git a/lxcfs.c b/lxcfs.c
index 85719aa60aea66d2d0f922a88b608827dfab025d..2fed3a71213f1d56be0694121ba3bd5a55ec35bd 100644 (file)
--- a/lxcfs.c
+++ b/lxcfs.c
@@ -55,6 +55,7 @@ struct file_info {
        char *buf;  // unused as of yet
        int buflen;
        int size; //actual data size
+       int cached;
 };
 
 /* reserve buffer size, for cpuall in /proc/stat */
@@ -1858,6 +1859,8 @@ static int proc_meminfo_read(char *buf, size_t size, off_t offset,
        if (offset){
                if (offset > d->size)
                        return -EINVAL;
+               if (!d->cached)
+                       return 0;
                int left = d->size - offset;
                total_len = left > size ? size: left;
                memcpy(buf, cache + offset, total_len);
@@ -1931,6 +1934,7 @@ static int proc_meminfo_read(char *buf, size_t size, off_t offset,
                total_len += l;
        }
 
+       d->cached = 1;
        d->size = total_len;
        if (total_len > size ) total_len = size;
        memcpy(buf, d->buf, total_len);
@@ -2001,6 +2005,8 @@ static int proc_cpuinfo_read(char *buf, size_t size, off_t offset,
        if (offset){
                if (offset > d->size)
                        return -EINVAL;
+               if (!d->cached)
+                       return 0;
                int left = d->size - offset;
                total_len = left > size ? size: left;
                memcpy(buf, cache + offset, total_len);
@@ -2074,6 +2080,7 @@ static int proc_cpuinfo_read(char *buf, size_t size, off_t offset,
                }
        }
 
+       d->cached = 1;
        d->size = total_len;
        if (total_len > size ) total_len = size;
 
@@ -2112,6 +2119,8 @@ static int proc_stat_read(char *buf, size_t size, off_t offset,
        if (offset){
                if (offset > d->size)
                        return -EINVAL;
+               if (!d->cached)
+                       return 0;
                int left = d->size - offset;
                total_len = left > size ? size: left;
                memcpy(buf, d->buf + offset, total_len);
@@ -2224,6 +2233,7 @@ static int proc_stat_read(char *buf, size_t size, off_t offset,
 
        memmove(cache, d->buf + CPUALL_MAX_SIZE, total_len);
        total_len += cpuall_len;
+       d->cached = 1;
        d->size = total_len;
        if (total_len > size ) total_len = size;
 
@@ -2417,25 +2427,32 @@ static int proc_uptime_read(char *buf, size_t size, off_t offset,
        struct file_info *d = (struct file_info *)fi->fh;
        long int reaperage = getreaperage(fc->pid);;
        unsigned long int idletime = getprocidle();
+       char *cache = d->buf;
        size_t total_len = 0;
 
        if (offset){
                if (offset > d->size)
                        return -EINVAL;
-               return 0;
+               if (!d->cached)
+                       return 0;
+               int left = d->size - offset;
+               total_len = left > size ? size: left;
+               memcpy(buf, cache + offset, total_len);
+               return total_len;
        }
 
-       total_len = snprintf(buf, size, "%ld.0 %lu.0\n", reaperage, idletime);
+       total_len = snprintf(d->buf, d->size, "%ld.0 %lu.0\n", reaperage, idletime);
        if (total_len < 0){
                perror("Error writing to cache");
                return 0;
        }
-       if (total_len >= size){
-               d->size = size;
-               return size;
-       }
 
-       d->size = total_len;
+       d->size = (int)total_len;
+       d->cached = 1;
+
+       if (total_len > size) total_len = size;
+
+       memcpy(buf, d->buf, total_len);
        return total_len;
 }
 
@@ -2454,6 +2471,8 @@ static int proc_diskstats_read(char *buf, size_t size, off_t offset,
        unsigned long read_ticks = 0, write_ticks = 0;
        unsigned long ios_pgr = 0, tot_ticks = 0, rq_ticks = 0;
        unsigned long rd_svctm = 0, wr_svctm = 0, rd_wait = 0, wr_wait = 0;
+       char *cache = d->buf;
+       size_t cache_size = d->buflen;
        char *line = NULL;
        size_t linelen = 0, total_len = 0, rv = 0;
        unsigned int major = 0, minor = 0;
@@ -2463,7 +2482,12 @@ static int proc_diskstats_read(char *buf, size_t size, off_t offset,
        if (offset){
                if (offset > d->size)
                        return -EINVAL;
-               return 0;
+               if (!d->cached)
+                       return 0;
+               int left = d->size - offset;
+               total_len = left > size ? size: left;
+               memcpy(buf, cache + offset, total_len);
+               return total_len;
        }
 
        cg = get_pid_cgroup(fc->pid, "blkio");
@@ -2528,23 +2552,27 @@ static int proc_diskstats_read(char *buf, size_t size, off_t offset,
                } else
                        continue;
 
-               l = snprintf(buf, size, "%s", printme);
+               l = snprintf(cache, cache_size, "%s", printme);
                if (l < 0) {
                        perror("Error writing to fuse buf");
                        rv = 0;
                        goto err;
                }
-               if (l >= size) {
+               if (l >= cache_size) {
                        fprintf(stderr, "Internal error: truncated write to cache\n");
                        rv = 0;
                        goto err;
                }
-               buf += l;
-               size -= l;
+               cache += l;
+               cache_size -= l;
                total_len += l;
        }
 
+       d->cached = 1;
        d->size = total_len;
+       if (total_len > size ) total_len = size;
+       memcpy(buf, d->buf, total_len);
+
        rv = total_len;
 err:
        free(cg);