git/pager.c, branch v2.6.2

Merge branch 'ti/glibc-stdio-mutex-from-signal-handler' into maint

2015-10-16T21:32:41Z

Allocation related functions and stdio are unsafe things to call inside a signal handler, and indeed killing the pager can cause glibc to deadlock waiting on allocation mutex as our signal handler tries to free() some data structures in wait_for_pager(). Reduce these unsafe calls. * ti/glibc-stdio-mutex-from-signal-handler: pager: don't use unsafe functions in signal handlers

pager: don't use unsafe functions in signal handlers

2015-09-04T21:57:51Z

Since the commit a3da8821208d (pager: do wait_for_pager on signal death), we call wait_for_pager() in the pager's signal handler. The recent bug report revealed that this causes a deadlock in glibc at aborting "git log" [*1*]. When this happens, git process is left unterminated, and it can't be killed by SIGTERM but only by SIGKILL. The problem is that wait_for_pager() function does more than waiting for pager process's termination, but it does cleanups and printing errors. Unfortunately, the functions that may be used in a signal handler are very limited [*2*]. Particularly, malloc(), free() and the variants can't be used in a signal handler because they take a mutex internally in glibc. This was the cause of the deadlock above. Other than the direct calls of malloc/free, many functions calling malloc/free can't be used. strerror() is such one, either. Also the usage of fflush() and printf() in a signal handler is bad, although it seems working so far. In a safer side, we should avoid them, too. This patch tries to reduce the calls of such functions in signal handlers. wait_for_signal() takes a flag and avoids the unsafe calls. Also, finish_command_in_signal() is introduced for the same reason. There the free() calls are removed, and only waits for the children without whining at errors. [*1*] https://bugzilla.opensuse.org/show_bug.cgi?id=942297 [*2*] http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04_03 Signed-off-by: Takashi Iwai Reviewed-by: Jeff King Signed-off-by: Junio C Hamano

Merge branch 'jk/fix-alias-pager-config-key-warnings'

2015-08-31T22:38:57Z

Because the configuration system does not allow "alias.0foo" and "pager.0foo" as the configuration key, the user cannot use '0foo' as a custom command name anyway, but "git 0foo" tried to look these keys up and emitted useless warnings before saying '0foo is not a git command'. These warning messages have been squelched. * jk/fix-alias-pager-config-key-warnings: config: silence warnings for command names with invalid keys

config: silence warnings for command names with invalid keys

2015-08-24T15:52:23Z

When we are running the git command "foo", we may have to look up the config keys "pager.foo" and "alias.foo". These config schemes are mis-designed, as the command names can be anything, but the config syntax has some restrictions. For example: $ git foo_bar error: invalid key: pager.foo_bar error: invalid key: alias.foo_bar git: 'foo_bar' is not a git command. See 'git --help'. You cannot name an alias with an underscore. And if you have an external command with one, you cannot configure its pager. In the long run, we may develop a different config scheme for these features. But in the near term (and because we'll need to support the existing scheme indefinitely), we should at least squelch the error messages shown above. These errors come from git_config_parse_key. Ideally we would pass a "quiet" flag to the config machinery, but there are many layers between the pager code and the key parsing. Passing a flag through all of those would be an invasive change. Instead, let's provide a config function to report on whether a key is syntactically valid, and have the pager and alias code skip lookup for bogus keys. We can build this easily around the existing git_config_parse_key, with two minor modifications: 1. We now handle a NULL store_key, to validate but not write out the normalized key. 2. We accept a "quiet" flag to avoid writing to stderr. This doesn't need to be a full-blown public "flags" field, because we can make the existing implementation a static helper function, keeping the mess contained inside config.c. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

Merge branch 'jc/unexport-git-pager-in-use-in-pager'

2015-07-13T21:00:27Z

When you say "!" while running say "git log", you'd confuse yourself in the resulting shell, that may look as if you took control back to the original shell you spawned "git log" from but that isn't what is happening. To that new shell, we leaked GIT_PAGER_IN_USE environment variable that was meant as a local communication between the original "Git" and subprocesses that was spawned by it after we launched the pager, which caused many "interesting" things to happen, e.g. "git diff | cat" still paints its output in color by default. Stop leaking that environment variable to the pager's half of the fork; we only need it on "Git" side when we spawn the pager. * jc/unexport-git-pager-in-use-in-pager: pager: do not leak "GIT_PAGER_IN_USE" to the pager

pager: do not leak "GIT_PAGER_IN_USE" to the pager

2015-07-04T01:07:21Z

Since 2e6c012e (setup_pager: set GIT_PAGER_IN_USE, 2011-08-17), we export GIT_PAGER_IN_USE so that a process that becomes the upstream of the spawned pager can still tell that we have spawned the pager and decide to do colored output even when its output no longer goes to a terminal (i.e. isatty(1)). But we forgot to clear it from the enviornment of the spawned pager. This is not a problem in a sane world, but if you have a handful of thousands Git users in your organization, somebody is bound to do strange things, e.g. typing "!" instead of 'q' to get control back from $LESS. GIT_PAGER_IN_USE is still set in that subshell spawned by "less", and all sorts of interesting things starts happening, e.g. "git diff | cat" starts coloring its output. We can clear the environment variable in the half of the fork that runs the pager to avoid the confusion. Signed-off-by: Junio C Hamano Acked-by: Jeff King Signed-off-by: Junio C Hamano

Merge branch 'jk/decimal-width-for-uintmax'

2015-02-18T19:45:02Z

We didn't format an integer that wouldn't fit in "int" but in "uintmax_t" correctly. * jk/decimal-width-for-uintmax: decimal_width: avoid integer overflow

decimal_width: avoid integer overflow

2015-02-05T20:38:35Z

The decimal_width function originally appeared in blame.c as "lineno_width", and was designed for calculating the print-width of small-ish integer values (line numbers in text files). In ec7ff5b, it was made into a reusable function, and in dc801e7, we started using it to align diffstats. Binary files in a diffstat show byte counts rather than line numbers, meaning they can be quite large (e.g., consider adding or removing a 2GB file). decimal_width is not up to the challenge for two reasons: 1. It takes the value as an "int", whereas large files may easily surpass this. The value may be truncated, in which case we will produce an incorrect value. 2. It counts "up" by repeatedly multiplying another integer by 10 until it surpasses the value. This can cause an infinite loop when the value is close to the largest representable integer. For example, consider using a 32-bit signed integer, and a value of 2,140,000,000 (just shy of 2^31-1). We will count up and eventually see that 1,000,000,000 is smaller than our value. The next step would be to multiply by 10 and see that 10,000,000,000 is too large, ending the loop. But we can't represent that value, and we have signed overflow. This is technically undefined behavior, but a common behavior is to lose the high bits, in which case our iterator will certainly be less than the number. So we'll keep multiplying, overflow again, and so on. This patch changes the argument to a uintmax_t (the same type we use to store the diffstat information for binary filese), and counts "down" by repeatedly dividing our value by 10. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

use env_array member of struct child_process

2014-10-19T22:26:34Z

Convert users of struct child_process to using the managed env_array for specifying environment variables instead of supplying an array on the stack or bringing their own argv_array. This shortens and simplifies the code and ensures automatically that the allocated memory is freed after use. Signed-off-by: Rene Scharfe Signed-off-by: Junio C Hamano

Merge branch 'rs/child-process-init'

2014-09-11T17:33:27Z

Code clean-up. * rs/child-process-init: run-command: inline prepare_run_command_v_opt() run-command: call run_command_v_opt_cd_env() instead of duplicating it run-command: introduce child_process_init() run-command: introduce CHILD_PROCESS_INIT