commit - ab9934da3316cf362e131acdcb2b3171ac7fbf5e
commit + 33aa3497b959ad985e7fb0f016da798f30f2eef0
blob - 2aa1ff329a9854a3546308a2478d50ba2765ef88
blob + 50db83dc79e5f1e7414070beb4d8af7607a5aeeb
--- README.md
+++ 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
 
blob - 30eeca1c904bafffd986784e482ba7cc4e28e3e3
blob + 217c01a4511b1b701ccc4797cc33df4cd314bbe8
--- unreliablefs-scm-1.rockspec
+++ 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 <estetus@gmail.com>",
blob - 624bc25cbc29c1d549c4793cb4762e4fffb54cb9
blob + 80dcc3cbdabbe540e7a9508a1c46da01b70bc22f
--- unreliablefs.conf.5
+++ 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 ,
blob - a069f4d30b8733e56219169b4b1fdef1463ff865
blob + 681de370bee5409a2d894725dac3f3e8b7c19dc2
--- unreliablefs_errinj.c
+++ unreliablefs_errinj.c
@@ -21,6 +21,7 @@ const char *errinj_name[] =
     "errinj_kill_caller",
     "errinj_noop",
     "errinj_slowdown",
+    "errinj_1byte_read",
 };
 
 typedef enum {
@@ -28,6 +29,7 @@ typedef enum {
     ERRINJ_KILL_CALLER,
     ERRINJ_NOOP,
     ERRINJ_SLOWDOWN,
+    ERRINJ_1BYTE_READ,
 } errinj_type;
 
 typedef struct errinj_conf errinj_conf;
@@ -262,6 +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;
         }
     }
 
blob - 299d5027cf13cf486938e683038b60e40fb351c7
blob + 4889de8d7338eb0cba5c6cfb742dce4469fb4e09
--- unreliablefs_errinj.h
+++ 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);
blob - f9d48d5620657020de0adbd34b01a2a66fc90241
blob + 2c20d7d3e8f7c14556e8854760919a4e48ef5551
--- unreliablefs_ops.c
+++ unreliablefs_ops.c
@@ -317,6 +317,8 @@ int unreliable_read(const char *path, char *buf, size_
     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;
     }