Add fault injection with 1-byte reads

README.md

@@ -13,6 +13,8 @@ Supported fault injections are:
   (similar to [libeatmydata](https://github.com/stewartsmith/libeatmydata),
   but applicable to any file operation).
 - `errinj_slowdown` - slowdown invoked file operation.
+- `errinj_1byte_read` - amount of data returned by `read()` call is always
+  limited by a single byte.
 
 ### Building
 

unreliablefs-scm-1.rockspec

@@ -13,6 +13,8 @@ description = {
     - `errinj_kill_caller` - send SIGKILL to a process that invoked file operation;
     - `errinj_noop` - replace file operation with no operation;
     - `errinj_slowdown` - slowdown invoked file operation;
+    - `errinj_1byte_read` - amount of data returned by `read()` call is always
+    limited by a single byte.
     ]],
     homepage = "https://github.com/ligurio/unreliablefs",
     maintainer = "Sergey Bronnikov <[email protected]>",

unreliablefs.conf.5

@@ -36,6 +36,10 @@ Set random errno.
 limited by supported errno's.
 .It Cm errinj_slowdown
 File operation slowdown for nanoseconds specified by duration parameter.
+.It Cm errinj_1byte_read
+Return exactly 1 byte on every
+.Xr read 2
+operation.
 .El
 .Pp
 The options are:
@@ -69,6 +73,10 @@ probability = 70
 path_regexp = *.xlog
 probability = 4
 
+[errinj_1byte_read]
+path_regexp = *.xlog
+probability = 100
+
 .Ed
 .Sh SEE ALSO
 .Xr unreliablefs 1 ,

unreliablefs_errinj.c

@@ -15,6 +15,39 @@
 #include "unreliablefs.h"
 #include "unreliablefs_errinj.h"
 
+const char *errinj_name[] =
+{
+    "errinj_errno",
+    "errinj_kill_caller",
+    "errinj_noop",
+    "errinj_slowdown",
+    "errinj_1byte_read",
+};
+
+typedef enum {
+    ERRINJ_ERRNO,
+    ERRINJ_KILL_CALLER,
+    ERRINJ_NOOP,
+    ERRINJ_SLOWDOWN,
+    ERRINJ_1BYTE_READ,
+} errinj_type;
+
+typedef struct errinj_conf errinj_conf;
+
+struct errinj_conf {
+    char *err_injection_name;
+    char *op_regexp;
+    char *path_regexp;
+    char *errno_regexp;
+    unsigned int probability;
+    unsigned int duration;
+    errinj_type type;
+
+    TAILQ_ENTRY(errinj_conf) entries;
+};
+
+TAILQ_HEAD(err_inj_q, errinj_conf);
+
 static int rand_range(int, int);
 int error_inject(const char* path, fuse_op operation);
 
@@ -231,6 +264,11 @@ int error_inject(const char* path, fuse_op operation)
 		fprintf(stdout, "end of '%s' slowdown with '%d' ns\n", op_name, err->duration);
             }
             break;
+        case ERRINJ_1BYTE_READ:
+            fprintf(stdout, "start of 1-byte read\n");
+            if (strcmp(op_name, "read") == 0)
+                rc = -ERRINJ_1BYTE_READ;
+            break;
         }
     }
 

unreliablefs_errinj.h

@@ -22,6 +22,7 @@
 #define MIN_PROBABLITY 0
 #define MAX_PROBABLITY 100
 #define ERRNO_NOOP -999
+#define ERRNO_1BYTE_READ -998
 #define DEFAULT_SIGNAL_NAME SIGKILL
 
 int error_inject(const char* path, fuse_op operation);
@@ -31,35 +32,4 @@ int conf_option_handler(void* cfg, const char* section,
                         const char* name, const char* value);
 int is_regex_matched(const char *regex, const char *string);
 
-const char *errinj_name[] =
-{
-    "errinj_errno",
-    "errinj_kill_caller",
-    "errinj_noop",
-    "errinj_slowdown",
-};
-
-typedef enum {
-    ERRINJ_ERRNO,
-    ERRINJ_KILL_CALLER,
-    ERRINJ_NOOP,
-    ERRINJ_SLOWDOWN,
-} errinj_type;
-
-typedef struct errinj_conf errinj_conf;
-
-struct errinj_conf {
-    char *err_injection_name;
-    char *op_regexp;
-    char *path_regexp;
-    char *errno_regexp;
-    unsigned int probability;
-    unsigned int duration;
-    errinj_type type;
-
-    TAILQ_ENTRY(errinj_conf) entries;
-};
-
-TAILQ_HEAD(err_inj_q, errinj_conf);
-
 #endif /* ERRINJ_HH */

unreliablefs_ops.c

@@ -16,9 +16,8 @@
 #define _XOPEN_SOURCE 700
 #endif
 
-#define ERRNO_NOOP -999
-
 #include "unreliablefs_ops.h"
+#include "unreliablefs_errinj.h"
 
 const char *fuse_op_name[] = {
     "getattr",
@@ -318,6 +317,8 @@ int unreliable_read(const char *path, char *buf, size_t size, off_t offset,
     int ret = error_inject(path, OP_READ);
     if (ret == -ERRNO_NOOP) {
         return 0;
+    } else if (ret == -ERRNO_1BYTE_READ) {
+        size = 1;
     } else if (ret) {
         return ret;
     }