sleep: fix SIGINFO output and modernize interval parsing

[nvsrahul_hotmail.com]

Summary

Replace sscanf-based interval parsing with strtod(3) to match
documented behavior and improve error handling. Fix SIGINFO
handling to print remaining sleep time to stdout as specified
by sleep(1).

Signed-off-by: NVSRahul <[e-mail]>

Test Plan

Tested interval parsing with integer and fractional values
using s, m, h, and d units. Verified invalid inputs are rejected.
Confirmed SIGINFO output is printed to stdout and works correctly
with stdout redirection.

[nvsrahul_hotmail.com]

• sleep: fix SIGINFO output and modernize interval parsing

[nvsrahul_hotmail.com]

Updating D54765: sleep: fix SIGINFO output and modernize interval parsing

[nvsrahul_hotmail.com]

Updating D54765: sleep: fix SIGINFO output and modernize interval parsing

[nvsrahul_hotmail.com]

Updating D54765: sleep: fix SIGINFO output and modernize interval parsing

[nvsrahul_hotmail.com]

Updating D54765: sleep: fix SIGINFO output and modernize interval parsing

[nvsrahul_hotmail.com]

Updating D54765: sleep: fix SIGINFO output and modernize interval parsing

[nvsrahul_hotmail.com]

Updated D54765: sleep: fix SIGINFO output and modernize interval parsing

[imp]

bin/sleep/sleep.c

92

So if endptr[0] was NUL, what guarantees endptr[1] is also NUL.

[nvsrahul_hotmail.com]

Updated D54765: sleep: fix SIGINFO output and modernize interval parsing

[nvsrahul_hotmail.com]

Good catch, thanks.
When *endptr == '\0', accessing endptr[1] is invalid.
I’ve updated the logic to only check endptr[1] when a unit
character is present, avoiding a read past the string terminator.