This is a respin on an old patchset [1] which is no longer on patchwork. The main change is just a rebase against master since glibc version is now on sync with gnulib.
I am sending it also to gnulib to get feedback from the project, specifically for the part not specific for the system support by glibc and extra requirements. The idea of removing the alloca allows a slight better code generation, simplifies the boilerplate code to avoid the unbounded alloca usage, and it plays better with security compiler mitigation tools (such as the ones for stack clash). On x86_64 with gcc 9.2.1 build glob for shared object, the total stack usage went from: glob.c:261:1:next_brace_sub 8 static glob.c:1205:1:prefix_array 96 static glob.c:1185:1:collated_compare 8 static glob.c:250:1:is_dir.isra.0 160 static glob.c:1259:1:glob_in_dir 864 dynamic glob.c:297:1:__glob 1360 dynamic to glob.c:231:1:next_brace_sub 8 static dynarray-skeleton.c:203:1:globnames_array_free 32 static glob.c:1131:1:prefix_array 96 static glob.c:1111:1:collated_compare 8 static dynarray-skeleton.c:275:1:globnames_array_add__ 48 static dynarray-skeleton.c:373:1:char_array_resize.part.0 48 static char_array-skeleton.c:274:1:char_array_replace_str_pos 48 static char_array-skeleton.c:204:1:char_array_crop 32 static char_array-skeleton.c:240:1:char_array_append_str 48 static char_array-skeleton.c:118:1:char_array_set_str_size 32 static char_array-skeleton.c:161:1:char_array_init_str 32 static glob.c:220:1:is_dir.isra.0 160 static glob.c:1200:1:glob_in_dir 1088 static glob.c:267:1:__glob 1824 static (it was obtained with -fstack-usage gcc option). It is a slight increase and due GNU extension where glob might be called recursivelly internally the total stack usage might be still slight larger than current implementation. But I still think it is a worth tradeoff. [1] https://sourceware.org/pipermail/libc-alpha/2018-February/091326.html Adhemerval Zanella (8): malloc: Add specialized dynarray for C strings posix: Use char_array for internal glob dirname posix: Remove alloca usage for GLOB_BRACE on glob posix: Remove alloca usage on glob dirname posix: Use dynarray for globname in glob posix: Remove alloca usage on glob user_name posix: Use char_array for home_dir in glob posix: Remove all alloca usage in glob malloc/Makefile | 4 +- malloc/Versions | 7 + malloc/char_array-impl.c | 57 +++ malloc/char_array-skeleton.c | 288 +++++++++++++ malloc/char_array.h | 53 +++ malloc/dynarray.h | 9 + malloc/dynarray_overflow_failure.c | 31 ++ malloc/malloc-internal.h | 14 + malloc/tst-char_array.c | 112 ++++++ posix/glob.c | 622 +++++++++++------------------ 10 files changed, 817 insertions(+), 380 deletions(-) create mode 100644 malloc/char_array-impl.c create mode 100644 malloc/char_array-skeleton.c create mode 100644 malloc/char_array.h create mode 100644 malloc/dynarray_overflow_failure.c create mode 100644 malloc/tst-char_array.c -- 2.25.1
