amiga-fdisk: ftbfs with GCC-14

[Christian T. Steigies]

Hi,
I need to fix this bug if we want to have amiga-fdisk in trixie:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1074807

The attached patch fixes the error and removes one of the warnings, I assume
that this is the correct solution?


There are a couple more warnings which will probably become errors in one of
the next gcc releases (We are at version 14? The last GCC version I
remember using was something like 2.9, and I still have 2.6.3 on 10 floppy
disks somewhere...). I am not sure how to get rid of those warnings.


gcc -g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/home/cts/salsa/amiga-fdisk=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wall -pedantic -DUSE_READLINE=yes -I./include -Wdate-time -D_FORTIFY_SOURCE=2 -c -o amigastuff.o amigastuff.c
amigastuff.c: In function ‘rigiddisk_reorg’:
amigastuff.c:859:20: warning: pointer targets in assignment from ‘LONG *’ {aka ‘long int *’} to ‘ULONG *’ {aka ‘long unsigned int *’} differ in signedness [-Wpointer-sign]
859 | crk=&(FSHB(curr)->fhb_SegListBlocks);
| ^
gcc -g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/home/cts/salsa/amiga-fdisk=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wall -pedantic -DUSE_READLINE=yes -I./include -Wdate-time -D_FORTIFY_SOURCE=2 -c -o fdisk.o fdisk.c
fdisk.c: In function ‘atonum’:
fdisk.c:85:33: warning: format ‘%x’ expects argument of type ‘unsigned int *’, but argument 3 has type ‘int *’ [-Wformat=]
85 | sscanf(s + 2, "%x", &n);
| ~^ ~~
| | |
| | int *
| unsigned int *
| %x
fdisk.c:87:33: warning: format ‘%o’ expects argument of type ‘unsigned int *’, but argument 3 has type ‘int *’ [-Wformat=]
87 | sscanf(s + 1, "%o", &n);
| ~^ ~~
| | |
| | int *
| unsigned int *
| %o

I tried defining n in fdisk.c as unsigned int but this caused even more
warnings in other places. Do I have to cast the arguments in sscanf to
unsigned int? It wants "unsigned int *", is it as simple as this or is
there a better solution?

--- a/fdisk.c
+++ b/fdisk.c
@@ -82,9 +82,9 @@

/* 0x is hex, 0 is octal, everything else is decimal. */
if (strncmp(s, "0x", 2) == 0 || strncmp(s, "0X", 2) == 0)
- sscanf(s + 2, "%x", &n);
+ sscanf(s + 2, "%x", (unsigned int *) &n);
else if (s[0] == '0' && s[1])
- sscanf(s + 1, "%o", &n);
+ sscanf(s + 1, "%o", (unsigned int *) &n);
else {
d=s;
while (d[0]!=0) {



thanks,
Christian

[John Paul Adrian Glaubitz]

Hi Christian,

Post by Christian T. Steigies
gcc -g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/home/cts/salsa/amiga-fdisk=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wall -pedantic -DUSE_READLINE=yes -I./include -Wdate-time -D_FORTIFY_SOURCE=2 -c -o amigastuff.o amigastuff.c
amigastuff.c:859:20: warning: pointer targets in assignment from ‘LONG *’ {aka ‘long int *’} to ‘ULONG *’ {aka ‘long unsigned int *’} differ in signedness [-Wpointer-sign]
859 | crk=&(FSHB(curr)->fhb_SegListBlocks);
| ^

In this case, you should just declare your variable such that it matches the function call.

Switching between signed and unsigned without proper conversion is not a good idea in general.

Post by Christian T. Steigies
gcc -g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/home/cts/salsa/amiga-fdisk=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wall -pedantic -DUSE_READLINE=yes -I./include -Wdate-time -D_FORTIFY_SOURCE=2 -c -o fdisk.o fdisk.c
fdisk.c:85:33: warning: format ‘%x’ expects argument of type ‘unsigned int *’, but argument 3 has type ‘int *’ [-Wformat=]
85 | sscanf(s + 2, "%x", &n);
| ~^ ~~
| | |
| | int *
| unsigned int *
| %x
fdisk.c:87:33: warning: format ‘%o’ expects argument of type ‘unsigned int *’, but argument 3 has type ‘int *’ [-Wformat=]
87 | sscanf(s + 1, "%o", &n);
| ~^ ~~
| | |
| | int *
| unsigned int *
| %o
I tried defining n in fdisk.c as unsigned int but this caused even more
warnings in other places. Do I have to cast the arguments in sscanf to
unsigned int? It wants "unsigned int *", is it as simple as this or is
there a better solution?
https://en.cppreference.com/w/c/io/fprintf
https://www.ibm.com/docs/en/zos/2.4.0?topic=files-inttypesh-io-format-integer-types
https://github.com/ibm-power-utilities/powerpc-utils/commit/b46743ca68b6a06a2c82de4048d94d3d5191717f

It can be a bit tricky to find the proper format specifier. When testing the change,
make sure to test build on both 32- and 64-bit systems as well as little- and big-
endian.

I would recommend to test on powerpc and ppc64 (perotto.debian.net) and barriere.debian.org
(i386 and amd64).

Adrian

[Geert Uytterhoeven]

Hi Adrian,

On Thu, Aug 15, 2024 at 11:44 PM John Paul Adrian Glaubitz

Post by Christian T. Steigies
gcc -g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/home/cts/salsa/amiga-fdisk=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wall -pedantic -DUSE_READLINE=yes -I./include -Wdate-time -D_FORTIFY_SOURCE=2 -c -o fdisk.o fdisk.c
fdisk.c:85:33: warning: format ‘%x’ expects argument of type ‘unsigned int *’, but argument 3 has type ‘int *’ [-Wformat=]
85 | sscanf(s + 2, "%x", &n);
| ~^ ~~
| | |
| | int *
| unsigned int *
| %x
fdisk.c:87:33: warning: format ‘%o’ expects argument of type ‘unsigned int *’, but argument 3 has type ‘int *’ [-Wformat=]
87 | sscanf(s + 1, "%o", &n);
| ~^ ~~
| | |
| | int *
| unsigned int *
| %o
I tried defining n in fdisk.c as unsigned int but this caused even more
warnings in other places. Do I have to cast the arguments in sscanf to
unsigned int? It wants "unsigned int *", is it as simple as this or is
there a better solution?

"%x" and "%o" always operate on unsigned values. There are no
format specifiers for signed hexadecimal and octal values, unlike for
decimal values ("%u" vs. "%d").

Gr{oetje,eeting}s,

Geert

[John Paul Adrian Glaubitz]

Hi,

Post by Geert Uytterhoeven

Post by Christian T. Steigies
I tried defining n in fdisk.c as unsigned int but this caused even more
warnings in other places. Do I have to cast the arguments in sscanf to
unsigned int? It wants "unsigned int *", is it as simple as this or is
there a better solution?

"%x" and "%o" always operate on unsigned values. There are no
format specifiers for signed hexadecimal and octal values, unlike for
decimal values ("%u" vs. "%d").

OK, so if the numbers are never supposed to be negative, then the variables should
be declared as unsigned in the first place. I would avoid casting the types as
this can often cause other problems.

Adrian