FreeCalypso > hg > freecalypso-tools
view target-utils/libcommon/cmdentry.c @ 465:003e48f8ebe1
rvinterf/etmsync/fsnew.c: cast 0 to (char *) for execl sentinel
I generally don't use NULL and use plain 0 instead, based on a "NULL
considered harmful" discussion on the classiccmp mailing list many aeons
ago (I couldn't find it, and I reason that it must have been 2005 or
earlier), but a recent complaint by a packager sent me searching, and I
found this:
https://ewontfix.com/11/
While I don't give a @#$% about "modern" systems and code-nazi tools,
I realized that passing a plain 0 as a pointer sentinel in execl is wrong
because it will break on systems where pointers are longer than the plain
int type. Again, I don't give a @#$% about the abomination of x86_64 and
the like, but if anyone ever manages to port my code to something like a
PDP-11 (16-bit int, 32-bit long and pointers), then passing a plain 0
as a function argument where a pointer is expected most definitely won't
work: if the most natural stack slot and SP alignment unit is 16 bits,
fitting an int, with longs and pointers taking up two such slots, then
the call stack will be totally wrong with a plain 0 passed for a pointer.
Casting the 0 to (char *) ought to be the most kosher solution for the
most retro systems possible.
author | Mychaela Falconia <falcon@freecalypso.org> |
---|---|
date | Mon, 11 Feb 2019 00:00:19 +0000 |
parents | e7502631a0f9 |
children |
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/* * This module implements ASCII command entry via the serial port, * with normal echo and minimal editing (rubout and kill). * * The command string buffer is bss-allocated here as well. It is * sized to allow a maximum-size S-record to be sent as a command, * as that is how we expect flash loading and XRAM chain-loading * to be done. */ #define MAXCMD 527 char command[MAXCMD+1]; /* * The command_entry() function takes no arguments, and begins by waiting * for serial input - hence the prompt should be printed before calling it. * * This function returns when one of the following characters is received: * CR - accepts the command * ^C or ^U - cancels the command * * The return value is non-zero if a non-empty command was accepted with CR, * or 0 if the user hit CR with no input or if the command was canceled * with ^C or ^U. In any case a CRLF is sent out the serial port * to close the input echo line before this function returns. */ command_entry() { int inlen, ch; for (inlen = 0; ; ) { ch = mygetchar(); if (ch >= ' ' && ch <= '~') { if (inlen < MAXCMD) { command[inlen++] = ch; putchar(ch); } else /* putchar(7) */; continue; } switch (ch) { case '\r': case '\n': command[inlen] = '\0'; putchar('\n'); return(inlen); case '\b': /* BS */ case 0x7F: /* DEL */ if (inlen) { putchar('\b'); putchar(' '); putchar('\b'); inlen--; } else /* putchar(7) */; continue; case 0x03: /* ^C */ putchar('^'); putchar('C'); putchar('\n'); return(0); case 0x15: /* ^U */ putchar('^'); putchar('U'); putchar('\n'); return(0); default: /* putchar(7) */; } } }