@@ gdb /home/proj/grep/b3.1/src/grep
GNU gdb (GDB) Fedora 7.11.1-86.fc24
...

For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from /home/proj/grep/b3.1/src/grep...done.
(gdb) set args . < fifo
(gdb) br reset
Breakpoint 1 at 0x4050c2: file ../../grep-3.1/src/grep.c, line 847.
(gdb) br grep.c:856 <==== break-point on "if (seek_failed)" in grep.c/reset()
Breakpoint 2 at 0x4055d6: file ../../grep-3.1/src/grep.c, line 856.
(gdb) run
Starting program: /home/proj/grep/b3.1/src/grep . < fifo
<GDB does not return because the open() call blocks>

    Using another terminal, execute: echo aaa > fifo (open() for write resumes the open() call above)

Missing separate debuginfos, use: dnf debuginfo-install glibc-2.23.1-12.fc24.x86_64
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".

Breakpoint 1, grep (ineof=<synthetic pointer>, st=0x7fffffffdaa0, fd=0) at ../../grep-3.1/src/grep.c:1447
1447      if (! reset (fd, st))
Missing separate debuginfos, use: dnf debuginfo-install pcre-8.41-1.fc24.x86_64
(gdb) cont
Continuing.

Breakpoint 2, reset (st=0x7fffffffdaa0, fd=0) at ../../grep-3.1/src/grep.c:856
856       if (seek_failed)
(gdb) p seek_failed
$1 = true
(gdb) p bufoffset
$2 = -1
(gdb) p errno
$3 = 29           # ESPIPE (= illegal seek)
(gdb) cont
Continuing.
aaa               # output of grep as expected/desired
[Inferior 1 (process 10652) exited normally]
(gdb)  quit
@@ 

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