5 ms·

> Of course, this only mocks the most basic features of the who command and doesn’t handle any option, like the famous `who am i` or `who mom hates`. it's not

> Of course, this only mocks the most basic features of the who command and doesn’t handle any option, like the famous `who am i` or `who mom hates`. it's not quite an apples to apples comparison as his rewrite doesn't handle any options or cleverness, but it's still a massive jump in LOC.

eesmith 6y ago
Nor is it anywhere near as portability. Though that's not a big issue these days.
- chard_slicks_ 6y ago
  If you don't care about all the features then Busybox's implementation will work fine at 170 lines inclusive of comments.
- eesmith 6y ago
  Wow, I touched a nerve I don't understand, to get a -1, so I'll explain myself. The GNU code looks like it's portable to a bunch of OSes, some with and some without a given feature. That sort of portability leads to having a lot of #ifdefs. If you're only going to support a handful of OSes - because that's all most people care about - then of course your code is going to be smaller. As a concrete example, the linked-to "who" uses: if (entry.ut_type != USER_PROCESS) continue; The GNU one uses: if (IS_USER_PROCESS (utmp_buf)) The IS_USER_PROCESS() macro is in gnulib's readutmp.h (which would need to be included in the overall line cound): # define IS_USER_PROCESS(U) \ (UT_USER (U)[0] \ && (UT_TYPE_USER_PROCESS (U) \ || (UT_TYPE_NOT_DEFINED && UT_TIME_MEMBER (U) != 0))) The UT_USER maps to ut_user on some systems, and ut_name on others: /* Accessor macro for the member named ut_user or ut_name. */ # if HAVE_UTMPX_H # if HAVE_STRUCT_UTMPX_UT_USER # define UT_USER(Utmp) ((Utmp)->ut_user) # endif # if HAVE_STRUCT_UTMPX_UT_NAME # undef UT_USER # define UT_USER(Utmp) ((Utmp)->ut_name) # endif This is because, as https://www.gnu.org/software/libc/manual/html_node/Logging-In-and-Out.html https://www.gnu.org/software/libc/manual/html_node/Logging-I... points out, "Note that the ut_user member of struct utmp is called ut_name in BSD. Therefore, ut_name is defined as an alias for ut_user in utmp.h" Each of those other macros supports cases where the machine supports a given test, and when it doesn't. Including for machines which don't implement ut_type! (That's what the UT_TYPE_NOT_DEFINED case is for, which falls back to using the time field ... which has its own set of variants!) Portability is neither options nor cleverness, so I added it to the list of considerations. But then again, most people now don't need to support decades of history and scores of Unix variants.
chard_slicks_ 6y ago
I know that it isn't a full implementation and my comment wasn't meant as a real comparison.

eesmith 6y ago

Nor is it anywhere near as portability. Though that's not a big issue these days.

chard_slicks_ 6y ago
If you don't care about all the features then Busybox's implementation will work fine at 170 lines inclusive of comments.
eesmith 6y ago
Wow, I touched a nerve I don't understand, to get a -1, so I'll explain myself. The GNU code looks like it's portable to a bunch of OSes, some with and some without a given feature. That sort of portability leads to having a lot of #ifdefs. If you're only going to support a handful of OSes - because that's all most people care about - then of course your code is going to be smaller. As a concrete example, the linked-to "who" uses: if (entry.ut_type != USER_PROCESS) continue; The GNU one uses: if (IS_USER_PROCESS (utmp_buf)) The IS_USER_PROCESS() macro is in gnulib's readutmp.h (which would need to be included in the overall line cound): # define IS_USER_PROCESS(U) \ (UT_USER (U)[0] \ && (UT_TYPE_USER_PROCESS (U) \ || (UT_TYPE_NOT_DEFINED && UT_TIME_MEMBER (U) != 0))) The UT_USER maps to ut_user on some systems, and ut_name on others: /* Accessor macro for the member named ut_user or ut_name. */ # if HAVE_UTMPX_H # if HAVE_STRUCT_UTMPX_UT_USER # define UT_USER(Utmp) ((Utmp)->ut_user) # endif # if HAVE_STRUCT_UTMPX_UT_NAME # undef UT_USER # define UT_USER(Utmp) ((Utmp)->ut_name) # endif This is because, as https://www.gnu.org/software/libc/manual/html_node/Logging-In-and-Out.html https://www.gnu.org/software/libc/manual/html_node/Logging-I... points out, "Note that the ut_user member of struct utmp is called ut_name in BSD. Therefore, ut_name is defined as an alias for ut_user in utmp.h" Each of those other macros supports cases where the machine supports a given test, and when it doesn't. Including for machines which don't implement ut_type! (That's what the UT_TYPE_NOT_DEFINED case is for, which falls back to using the time field ... which has its own set of variants!) Portability is neither options nor cleverness, so I added it to the list of considerations. But then again, most people now don't need to support decades of history and scores of Unix variants.

chard_slicks_ 6y ago

I know that it isn't a full implementation and my comment wasn't meant as a real comparison.