FreeCalypso > hg > freecalypso-tools
view rvinterf/etmsync/fsnew.c @ 465:003e48f8ebe1
rvinterf/etmsync/fsnew.c: cast 0 to (char *) for execl sentinel
I generally don't use NULL and use plain 0 instead, based on a "NULL
considered harmful" discussion on the classiccmp mailing list many aeons
ago (I couldn't find it, and I reason that it must have been 2005 or
earlier), but a recent complaint by a packager sent me searching, and I
found this:
https://ewontfix.com/11/
While I don't give a @#$% about "modern" systems and code-nazi tools,
I realized that passing a plain 0 as a pointer sentinel in execl is wrong
because it will break on systems where pointers are longer than the plain
int type. Again, I don't give a @#$% about the abomination of x86_64 and
the like, but if anyone ever manages to port my code to something like a
PDP-11 (16-bit int, 32-bit long and pointers), then passing a plain 0
as a function argument where a pointer is expected most definitely won't
work: if the most natural stack slot and SP alignment unit is 16 bits,
fitting an int, with longs and pointers taking up two such slots, then
the call stack will be totally wrong with a plain 0 passed for a pointer.
Casting the 0 to (char *) ought to be the most kosher solution for the
most retro systems possible.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Mon, 11 Feb 2019 00:00:19 +0000 |
parents | 0cb766828d7a |
children | 2cd5ac909e23 |
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/* * In this module we are going to implement the commands that upload * new FreeCalypso-invented stuff into the FFS of our FC devices. */ #include <sys/wait.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include "exitcodes.h" char batterytab_compile_tool[] = "/opt/freecalypso/bin/compile-fc-batt"; char charging_compile_tool[] = "/opt/freecalypso/bin/compile-fc-chg"; upload_fc_table_from_ascii(asciisrc, compiletool, ffs_pathname) char *asciisrc, *compiletool, *ffs_pathname; { char tmpfile[] = "/tmp/fc-fsioXXXXXX"; int tmpfd; pid_t child, waitres; int status, rc; tmpfd = mkstemp(tmpfile); if (tmpfd < 0) { fprintf(stderr, "unable to get temp file via mkstemp()\n"); return(ERROR_UNIX); } close(tmpfd); child = vfork(); if (child < 0) { fprintf(stderr, "unable to vfork to run compiler tool\n"); unlink(tmpfile); return(ERROR_UNIX); } if (!child) { execl(compiletool, compiletool, asciisrc, tmpfile, (char *) 0); perror(compiletool); _exit(ERROR_UNIX); } waitres = waitpid(child, &status, 0); if (waitres != child || !WIFEXITED(status)) { fprintf(stderr, "unexpected wait result after compiler run\n"); unlink(tmpfile); return(ERROR_UNIX); } rc = WEXITSTATUS(status); if (rc) { unlink(tmpfile); return rc; } rc = fwrite_from_file(ffs_pathname, tmpfile); unlink(tmpfile); return rc; } cmd_write_battery_table(argc, argv) char **argv; { return upload_fc_table_from_ascii(argv[1], batterytab_compile_tool, "/etc/batterytab"); } cmd_write_charging_config(argc, argv) char **argv; { return upload_fc_table_from_ascii(argv[1], charging_compile_tool, "/etc/charging"); }