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-rw-r--r--erts/emulator/drivers/common/efile_drv.c61
1 files changed, 58 insertions, 3 deletions
diff --git a/erts/emulator/drivers/common/efile_drv.c b/erts/emulator/drivers/common/efile_drv.c
index a1b15a2199..4e1d2f0d7f 100644
--- a/erts/emulator/drivers/common/efile_drv.c
+++ b/erts/emulator/drivers/common/efile_drv.c
@@ -1261,6 +1261,50 @@ static void free_read_line(void *data)
EF_FREE(d);
}
+void read_file_zero_size(struct t_data* d);
+#define ZERO_FILE_CHUNK (64 * 1024)
+
+/* [ERL-327] Some special files like /proc/... have reported size 0 */
+void read_file_zero_size(struct t_data* d) {
+ size_t total_read_size = 0;
+ size_t allocated_size = ZERO_FILE_CHUNK; /* allocd in invoke_read_file */
+ for (;;) {
+ size_t read_result;
+
+ /* Read until we hit EOF (read less than FILE_SEGMENT_READ) */
+ d->result_ok = efile_read(&d->errInfo,
+ EFILE_MODE_READ,
+ (int) d->fd,
+ (d->c.read_file.binp->orig_bytes +
+ total_read_size),
+ ZERO_FILE_CHUNK,
+ &read_result);
+ if (!d->result_ok) {
+ break;
+ }
+
+ total_read_size += read_result;
+ d->c.read_file.offset += read_result;
+ if (read_result < ZERO_FILE_CHUNK) {
+ break;
+ }
+
+ /* Grow before the next read call */
+ allocated_size = total_read_size + ZERO_FILE_CHUNK;
+ d->c.read_file.binp = driver_realloc_binary(d->c.read_file.binp,
+ allocated_size);
+ }
+
+ /* Finalize the memory usage. Hopefully it was read fully on the first
+ * go, so the binary allocation overhead becomes:
+ * alloc ZERO_FILE_CHUNK (64kb) -> realloc real_size */
+ if (allocated_size != total_read_size) {
+ d->c.read_file.binp = driver_realloc_binary(d->c.read_file.binp,
+ total_read_size);
+ }
+ d->again = 0;
+}
+
static void invoke_read_file(void *data)
{
struct t_data *d = (struct t_data *) data;
@@ -1279,9 +1323,15 @@ static void invoke_read_file(void *data)
}
d->fd = fd;
d->c.read_file.size = (int) size;
- if (size < 0 || size != d->c.read_file.size ||
- ! (d->c.read_file.binp =
- driver_alloc_binary(d->c.read_file.size))) {
+
+ /* For zero sized files allocate a reasonable chunk to attempt reading
+ * anyway. Note: This will eat ZERO_FILE_CHUNK bytes for any 0 file
+ * and free them immediately after (if the file was empty). */
+ ERTS_ASSERT(size >= 0);
+ d->c.read_file.binp = driver_alloc_binary(size != 0 ? (size_t)size
+ : ZERO_FILE_CHUNK);
+
+ if (size < 0 || size != d->c.read_file.size || !d->c.read_file.binp) {
d->result_ok = 0;
d->errInfo.posix_errno = ENOMEM;
goto close;
@@ -1290,6 +1340,11 @@ static void invoke_read_file(void *data)
}
/* Invariant: d->c.read_file.size >= d->c.read_file.offset */
+ if (d->c.read_file.size == 0) {
+ read_file_zero_size(d);
+ goto close;
+ }
+
read_size = (size_t) (d->c.read_file.size - d->c.read_file.offset);
if (! read_size) goto close;
chop = d->again && read_size >= FILE_SEGMENT_READ*2;