diff options
Diffstat (limited to 'functions.sh')
| -rw-r--r-- | functions.sh | 157 |
1 files changed, 93 insertions, 64 deletions
diff --git a/functions.sh b/functions.sh index 641deb6..43ea385 100644 --- a/functions.sh +++ b/functions.sh @@ -1,6 +1,6 @@ # Copyright 1999-2024 Gentoo Authors # Distributed under the terms of the GNU General Public License v2 -# shellcheck shell=sh disable=2209,3043 +# shellcheck shell=sh disable=2209,3013,3043 # This file contains a series of function declarations followed by some # initialisation code. Functions intended for internal use shall be prefixed @@ -294,17 +294,55 @@ is_anyof() # # Considers one or more pathnames and prints the one having the newest -# modification time. If at least one parameter is provided, all parameters shall -# be considered as pathnames to be compared to one another. Otherwise, the -# pathnames to be compared shall be read from the standard input as -# NUL-delimited records. If no pathnames are given, or those specified do not -# exist, the return value shall be greater than 0. In the case that two or more -# pathnames are candidates, the one having the lexicographically greatest value -# shall be selected. Pathnames containing newline characters shall be ignored. +# modification time. If at least one parameter is provided, all parameters +# shall be considered as pathnames to be compared to one another. Otherwise, +# the pathnames to be compared shall be read from the standard input as +# null-terminated records. In the case that two or more pathnames are +# candidates, whichever was first specified shall take precedence over the +# other. If no pathnames are given, or those specified do not exist, the return +# value shall be greater than 0. +# +# Pathnames containing <newline> characters shall be handled correctly if +# conveyed as positional parameters. Otherwise, the behaviour for such +# pathnames is unspecified. Users of the function are duly expected to refrain +# from conveying such pathnames for consumption from the standard input; for +# example, by specifying a predicate of ! -path $'*\n*' to the find utility. +# This constraint is expected to be eliminated by a future amendment to the +# function, once support for read -d becomes sufficiently widespread. +# +# The test utility is required to support the -nt primary, per POSIX-1.2024. +# However, measures are in place to to achieve compatibility with shells that +# implement the primary without yet fully adhering to the specification. # newest() { - _select_by_mtime -r "$@" + local path newest + + newest= + if [ "$#" -gt 0 ]; then + for path; do + # The tests within curly braces address a conformance + # issue whereby [ existent -nt nonexistent ] is + # incorrectly false. As of August 2024, busybox ash, + # dash, FreeBSD sh and NetBSD sh are known to be + # non-conforming in this respect. + if { [ ! "${newest}" ] && [ -e "${path}" ]; } || [ "${path}" -nt "${newest}" ]; then + newest=$path + fi + done + test "${newest}" && printf '%s\n' "${newest}" + else + # Support for read -d '' is not yet sufficiently widespread. + tr '\0' '\n' | + { + while IFS= read -r path; do + if { [ ! "${newest}" ] && [ -e "${path}" ]; } || [ "${path}" -nt "${newest}" ]; then + newest=$path + fi + done + test "${newest}" && printf '%s\n' "${newest}" + } + fi } # @@ -330,17 +368,55 @@ get_nprocs() # # Considers one or more pathnames and prints the one having the oldest -# modification time. If at least one parameter is provided, all parameters shall -# be considered as pathnames to be compared to one another. Otherwise, the -# pathnames to be compared shall be read from the standard input as -# NUL-delimited records. If no pathnames are given, or those specified do not -# exist, the return value shall be greater than 0. In the case that two or more -# pathnames are candidates, the one having the lexicographically lesser value -# shall be selected. Pathnames containing newline characters shall be ignored. +# modification time. If at least one parameter is provided, all parameters +# shall be considered as pathnames to be compared to one another. Otherwise, +# the pathnames to be compared shall be read from the standard input as +# null-terminated records. In the case that two or more pathnames are +# candidates, whichever was first specified shall take precedence over the +# other. If no pathnames are given, or those specified do not exist, the return +# value shall be greater than 0. +# +# Pathnames containing <newline> characters shall be handled correctly if +# conveyed as positional parameters. Otherwise, the behaviour for such +# pathnames is unspecified. Users of the function are duly expected to refrain +# from conveying such pathnames for consumption from the standard input; for +# example, by specifying a predicate of ! -path $'*\n*' to the find utility. +# This constraint is expected to be eliminated by a future amendment to the +# function, once support for read -d becomes sufficiently widespread. +# +# The test utility is required to support the -ot primary, per POSIX-1.2024. # oldest() { - _select_by_mtime -- "$@" + local path oldest + + oldest= + if [ "$#" -gt 0 ]; then + for path; do + # The specification has [ nonexistent -ot existent ] as + # being true. Such is a nuisance in this case but the + # preceding tests suffice as a workaround. + if [ ! -e "${path}" ]; then + continue + elif [ ! "${oldest}" ] || [ "${path}" -ot "${oldest}" ]; then + oldest=$path + fi + done + test "${oldest}" && printf '%s\n' "${oldest}" + else + # Support for read -d '' is not yet sufficiently widespread. + tr '\0' '\n' | + { + while IFS= read -r path; do + if [ ! -e "${path}" ]; then + continue + elif [ ! "${oldest}" ] || [ "${path}" -ot "${oldest}" ]; then + oldest=$path + fi + done + test "${oldest}" && printf '%s\n' "${oldest}" + } + fi } # @@ -676,34 +752,6 @@ whenceforth() #------------------------------------------------------------------------------# # -# See the definitions of _select_by_mtime() and is_older_than(). This function -# requires that GNU findutils >=4.9 be installed. -# -_find0() -{ - # Store the name of the GNU find binary, which may be "gfind". - hash gfind 2>/dev/null && genfun_bin_find=gfind || genfun_bin_find=find - - _find0() - { - local opt - - case $1 in - -[HL]) - opt=$1 - shift - set -- "${opt}" -files0-from - "$@" - ;; - *) - set -- -files0-from - "$@" - esac - "${genfun_bin_find}" "$@" - } - - _find0 "$@" -} - -# # Determines whether the terminal is a dumb one. # _has_dumb_terminal() @@ -735,25 +783,6 @@ if [ "${BASH_VERSINFO-0}" -ge 5 ]; then fi # -# See the definitions of oldest() and newest(). -# -_select_by_mtime() -{ - local sort_opt - - sort_opt=$1 - shift - if [ "$#" -gt 0 ]; then - printf '%s\0' "$@" - else - cat - fi \ - | _find0 -maxdepth 0 ! -path "*${genfun_newline}*" -printf '%T+ %p\n' \ - | sort "${sort_opt}" \ - | { IFS= read -r line && printf '%s\n' "${line#* }"; } -} - -# # Considers the first parameter as a number of centiseconds and determines # whether fewer have elapsed since the last occasion on which the function was # called, or whether the last genfun_time update resulted in integer overflow. |