Building Bash 1.14.7 on a modern system

In a previous revision of my Bash arrays post, I wrote:

Bash 1.x won’t compile with modern GCC, so I couldn’t verify how it behaves.

I recall spending a little time fighting with it, but apparently I didn’t try very hard: getting Bash 1.14.7 to build on a modern box is mostly just adjusting it to use stdarg instead of the no-longer-implemented varargs. There’s also a little fiddling with the pre-autoconf automatic configuration.

stdarg

Converting to stdarg is pretty simple: For each variadic function (functions that take a variable number of arguments), follow these steps:

1. Replace #include <varargs.h> with #include <stdarg.h>
2. Replace function_name (va_alist) va_dcl with function_name (char *format, ...).
3. Removing the declaration and assignment for format from the function body.
4. Replace va_start (args); with va_start (args, format); in the function bodies.
5. Replace function_name (); with function_name (char *, ...) in header files and/or at the top of C files.

There’s one function that uses the variable name control instead of format.

I’ve prepared a patch that does this.

Configuration

Instead of using autoconf-style tests to test for compiler and platform features, Bash 1 used the file machines.h that had #ifdefs and a huge database of of different operating systems for different platforms. It’s gross. And quite likely won’t handle your modern operating system.

I made these two small changes to machines.h to get it to work correctly on my box:

1. Replace #if defined (i386) with #if defined (i386) || defined (__x86_64__). The purpose of this is obvious.
2. Add #define USE_TERMCAP_EMULATION to the section for Linux [sic] on i386 (# if !defined (done386) && (defined (__linux__) || defined (linux))). What this does is tell it to link against libcurses to use curses termcap emulation, instead of linking against libtermcap (which doesn’t exist on modern GNU/Linux systems).

Again, I’ve prepared a patch that does this.

Building

With those adjustments, it should build, but with quite a few warnings. Making a couple of changes to CFLAGS should fix that:

make CFLAGS='-O -g -Werror -Wno-int-to-pointer-cast -Wno-pointer-to-int-cast -Wno-deprecated-declarations -include stdio.h -include stdlib.h -include string.h -Dexp2=bash_exp2'

That’s a doozy! Let’s break it down:

• -O -g The default value for CFLAGS (defined in cpp-Makefile)
• -Werror Treat warnings as errors; force us to deal with any issues.
• -Wno-int-to-pointer-cast -Wno-pointer-to-int-cast Allow casting between integers and pointers. Unfortunately, the way this version of Bash was designed requires this.
• -Wno-deprecated-declarations The getwd function in unistd.h is considered deprecated (use getcwd instead). However, if getcwd is available, Bash uses it’s own getwd wrapper around getcwd (implemented in general.c), and only uses the signature from unistd.h, not the actuall implementation from libc.
• -include stdio.h -include stdlib.h -include string.h Several files are missing these header file includes. If not for -Werror, the default function signature fallbacks would work.
• -Dexp2=bash_exp2 Avoid a conflict between the parser’s exp2 helper function and math.h’s base-2 exponential function.

Have fun, software archaeologists!