Remove unneeded calls to access(2) from rtld(1)

[trasz]

Summary

Remove unneeded calls to access(2) from rtld(1); just call open(2) instead.
The result looks like this:

--- przed       2017-10-21 23:19:21.445034000 +0100
+++ po  2017-10-21 23:18:50.031865000 +0100
@@ -11,7 +11,6 @@ mmap(0x0,102,PROT_READ,MAP_PRIVATE,3,0x0)      = 343665418
 close(3)                                        = 0 (0x0)
 open("/usr/local/etc/libmap.d",O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC,0165) ERR#2 'No such file or directory'
 munmap(0x80067d000,102)                                 = 0 (0x0)
-access("/usr/local/lib/libintl.so.8",F_OK)      = 0 (0x0)
 openat(AT_FDCWD,"/usr/local/lib/libintl.so.8",O_RDONLY|O_CLOEXEC|O_VERIFY,00) = 3 (0x3)
 fstat(3,{ mode=-rw-r--r-- ,inode=642560,size=55188,blksize=32768 }) = 0 (0x0)
 mmap(0x0,4096,PROT_READ,MAP_PRIVATE|MAP_PREFAULT_READ,3,0x0) = 34366541824 (0x80067d000)
@@ -20,14 +19,13 @@ mmap(0x800877000,40960,PROT_READ|PROT_EXEC,MAP_PRIVATE
 mmap(0x800a81000,4096,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_FIXED|MAP_PREFAULT_READ,3,0xa000) = 34370752512 (0x800a81000)
 munmap(0x80067d000,4096)                        = 0 (0x0)
 close(3)                                        = 0 (0x0)
-access("/usr/local/lib/libc.so.7",F_OK)                 ERR#2 'No such file or directory'
+openat(AT_FDCWD,"/usr/local/lib/libc.so.7",O_RDONLY|O_CLOEXEC|O_VERIFY,00) ERR#2 'No such file or directory'
 openat(AT_FDCWD,"/var/run/ld-elf.so.hints",O_RDONLY|O_CLOEXEC,00) = 3 (0x3)
 read(3,"Ehnt\^A\0\0\0\M^@\0\0\0\M-2\0\0"...,128) = 128 (0x80)
 fstat(3,{ mode=-r--r--r-- ,inode=970684,size=306,blksize=32768 }) = 0 (0x0)
 lseek(3,0x80,SEEK_SET)                          = 128 (0x80)
 read(3,"/lib:/usr/lib:/usr/lib/compat:/u"...,178) = 178 (0xb2)
 close(3)                                        = 0 (0x0)
-access("/lib/libc.so.7",F_OK)                   = 0 (0x0)
 openat(AT_FDCWD,"/lib/libc.so.7",O_RDONLY|O_CLOEXEC|O_VERIFY,00) = 3 (0x3)
 fstat(3,{ mode=-r--r--r-- ,inode=1605239,size=1910320,blksize=32768 }) = 0 (0x0)
 mmap(0x0,4096,PROT_READ,MAP_PRIVATE|MAP_PREFAULT_READ,3,0x0) = 34366541824 (0x80067d000)

[kib]

In principle, I do not object against this.

But the thing that makes me lunge is the fact that your trace shows the load of two libc.so.7 from different paths. I do not care about your (testing) configuration, but generally, rtld should not load two libraries with the same name. Can you re-check that this is not something introduced by your patch ?

libexec/rtld-elf/rtld.c

1644 ↗

(On Diff #34250)

The lines in these blocks are already too long, your patch enlarges them even more. The lines must be wrapped.

Also, since you change more than half of all function lines, use normal style(9) indents for the
find_library() function. Perhaps, do this in the preliminary commit.

Also, I suggest to extract assignments to pathname from the if () conditionals. I.e. do

pathname = search_library_path();
if (pathname != NULL)
  return (pathname);

3009 ↗

(On Diff #34250)

Fix style.

3051 ↗

(On Diff #34250)

Too many empty lines.

[trasz]

I only see one libc.so.7 - from /lib. There's an attempt to load it from /usr/local/lib, but that fails with ENOENT.

[kib]

In D12766#265000, @trasz wrote:

I only see one libc.so.7 - from /lib. There's an attempt to load it from /usr/local/lib, but that fails with ENOENT.

Ah, ok, it is before the system libc.so.7 is loaded. I misread the log.

I am fine with this in general, but see previous notes about style.

[trasz]

Rebase after commiting the style fixes.

[kib]

libexec/rtld-elf/rtld.c

3047 ↗

(On Diff #34279)

I suggest to complement the dbg statement with one after open to log error code or noting success.