Hello,
I am experiencing the same bug in Ubuntu 20.04 (Focal). My binfmtc
version is 0.17-2 and versions of gcc and g++ are :
gcc (Ubuntu 9.3.0-10ubuntu2) 9.3.0
g++ (Ubuntu 9.3.0-10ubuntu2) 9.3.0.
Here is output from running realcsh.c :
realcsh.c: In function ‘main’:
realcsh.c:96:7: warning: ignoring return value of ‘asprintf’, declared
with attribute warn_unused_result [-Wunused-result]
96 | asprintf(&tempfilename, "%s/realcshXXXXXX",
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
97 | getenv("BINFMTCTMPDIR")?:
| ~~~~~~~~~~~~~~~~~~~~~~~~~
98 | getenv("TMPDIR")?:
| ~~~~~~~~~~~~~~~~~~
99 | getenv("TEMPDIR")?:
| ~~~~~~~~~~~~~~~~~~~
100 | "/tmp"
| ~~~~~~
101 | );
| ~
realcsh.c:126:7: warning: ignoring return value of ‘system’, declared
with attribute warn_unused_result [-Wunused-result]
126 | system (tempfilename);
| ^~~~~~~~~~~~~~~~~~~~~
/usr/bin/ld: /tmp/ccRfBXnK.o: in function `main':
/usr/bin/realcsh.c:64: undefined reference to `readline'
/usr/bin/ld: /usr/bin/realcsh.c:72: undefined reference to
`add_history'
collect2: error: ld returned 1 exit status
binfmtc: Compilation failed for /usr/bin/realcsh.c, see above messages
for details
Possible fix :
If I set the variable BINFMTC_DEBUG to 1 by
export BINFMTC_DEBUG=1
I can see that binfmtc-interpreter executes :
binfmtc: Execute command-line: gcc -o /tmp/binfmtc0biaup -x c -
lreadline -I/usr/include/readline -O2 -Wall -g "realcsh.c"
This is not right and does not compile if I run the same command on the
terminal (with "realcsh.c" replaced by "/usr/bin/realcsh.c") and also
produces exactly the same error message as running realcsh.c (without
BINFMTC_DEBUG).
The proper order of gcc options, which compiles, is :
gcc -x c -O2 -Wall -g -I/usr/include/readline "/usr/bin/realcsh.c"
-lreadline -o /tmp/binfmtc0biaup
The -lreadline option should be before -o in order for the linking to
work.
