commit: 5f7d287e2aa996832c8fa31a9484e4d21dc29f90
Author: Kerin Millar <kfm <AT> plushkava <DOT> net>
AuthorDate: Thu Oct 9 07:52:39 2025 +0000
Commit: Sam James <sam <AT> gentoo <DOT> org>
CommitDate: Tue Oct 14 12:59:08 2025 +0000
URL:
https://gitweb.gentoo.org/proj/gentoo-functions.git/commit/?id=5f7d287e
Select an srandom() implementation upon being sourced
Presently, srandom() is defined as a self-redeclaring function, with the
the actual implementation being chosen upon its first invocation.
However, given that the function is highly likely to be invoked from a
command substitution, it isn't sensible to defer this choice.
Consider the following scenario.
num=$(srandom) # capture a random number
num=$(srandom) # capture a random number again
For both calls, srandom() will choose an implementation before
re-declaring and calling itself. That is, the initially chosen
implementation won't endure, since it only affects the subshell
environment that is incurred by the command substitution.
Address this minor issue by instead choosing an implementation at the
time that gentoo-functions is sourced.
Signed-off-by: Kerin Millar <kfm <AT> plushkava.net>
Signed-off-by: Sam James <sam <AT> gentoo.org>
functions.sh | 104 ++++++++++++++++++++++++++++-------------------------------
1 file changed, 49 insertions(+), 55 deletions(-)
diff --git a/functions.sh b/functions.sh
index 71d076d..02ee297 100644
--- a/functions.sh
+++ b/functions.sh
@@ -579,65 +579,59 @@ quote_args()
# the standard output along with a trailing <newline>. Otherwise, the return
# value shall be greater than 0.
#
-srandom()
-{
- # The SRANDOM variable was introduced by bash 5.1. Check for at least
- # 5.0 before comparing two expansions thereof. Doing so is safe because
- # bash discards numbers that are equal to whichever was last generated.
- #
- # shellcheck disable=3028
- if [ "${BASH_VERSINFO-0}" -ge 5 ] && [ "${SRANDOM}" != "${SRANDOM}" ];
then
- srandom()
- {
- printf '%d\n' "$(( SRANDOM >> 1 ))"
- }
- elif [ -c /dev/urandom ]; then
- # Employ a method which entails searching for 8 consecutive hex
- # digits, where the first is between 0 and 7.
-
genfun_int32_pat='[0-7][[:xdigit:]][[:xdigit:]][[:xdigit:]][[:xdigit:]][[:xdigit:]][[:xdigit:]][[:xdigit:]]'
- unset -v genfun_entropy
-
- srandom()
- {
- local hex i slice
+# shellcheck disable=3028
+if [ "${BASH_VERSINFO-0}" -ge 5 ] && [ "${SRANDOM}" != "${SRANDOM}" ]; then
+ # Take advantage of the SRANDOM variable, as introduced by bash 5.1.
+ srandom()
+ {
+ printf '%d\n' "$(( SRANDOM >> 1 ))"
+ }
+elif [ -c /dev/urandom ]; then
+ # Employ a method which entails searching for 8 consecutive hex digits,
+ # where the first is between 0 and 7.
+
genfun_int32_pat='[0-7][[:xdigit:]][[:xdigit:]][[:xdigit:]][[:xdigit:]][[:xdigit:]][[:xdigit:]][[:xdigit:]]'
+ unset -v genfun_entropy
- # If the shell has forked, or if it cannot be determined
- # whether it has done so, populate the pool with 64
- # bytes worth of fresh entropy.
- if ! _update_pid; then
+ srandom()
+ {
+ local hex i slice
+
+ # If the shell has forked, or if it cannot be determined
+ # whether it has done so, populate the pool with 64 bytes worth
+ # of fresh entropy.
+ if ! _update_pid; then
+ _collect_entropy
+ elif ! eval "test \"\${genfun_pool_${genfun_pid}+set}\""; then
+ _collect_entropy &&
+ eval "genfun_pool_${genfun_pid}=1"
+ fi || return
+
+ for i in 1 2 3; do
+ # shellcheck disable=2295
+ slice=${genfun_entropy%${genfun_int32_pat}*}
+ if [ "${#slice}" -ne "${#genfun_entropy}" ]; then
+ hex=${genfun_entropy#"$slice"}
+ genfun_entropy=${genfun_entropy%"$hex"}
+ while [ "${#hex}" -gt 8 ]; do
+ hex=${hex%?}
+ done
+ break
+ elif [ "$i" -lt 3 ]; then
+ # The pool does not contain a suitable
+ # sequence. Refill it then try again.
_collect_entropy
- elif ! eval "test
\"\${genfun_pool_${genfun_pid}+set}\""; then
- _collect_entropy &&
- eval "genfun_pool_${genfun_pid}=1"
- fi || return
-
- for i in 1 2 3; do
- # shellcheck disable=2295
- slice=${genfun_entropy%${genfun_int32_pat}*}
- if [ "${#slice}" -ne "${#genfun_entropy}" ];
then
- hex=${genfun_entropy#"$slice"}
- genfun_entropy=${genfun_entropy%"$hex"}
- while [ "${#hex}" -gt 8 ]; do
- hex=${hex%?}
- done
- break
- elif [ "$i" -lt 3 ]; then
- # The pool does not contain a suitable
- # sequence. Refill it then try again.
- _collect_entropy
- else
- false
- fi
- done &&
- printf '%d\n' "0x${hex}"
- }
- else
+ else
+ false
+ fi
+ done &&
+ printf '%d\n' "0x${hex}"
+ }
+else
+ srandom() {
warn "srandom: /dev/urandom doesn't exist as a character device"
return 1
- fi
-
- srandom
-}
+ }
+fi
#
# Trims leading and trailing whitespace from one or more lines. If at least one
