v0.2.0

- ent_install option to install locally (defaults to false.)

- Add pkg-config info if we're installing (hence the minor version
  bump.)

- Remove ENT_IMPL, making the preprocessor logic in ent.c more
  foolproof.

- Change meson.build style around a bit.

README.md

@@ -1,19 +1,25 @@
 libent is a cross-platform wrapper around `getentropy(2)`. It exports
-one symbol, `ent_getentropy`. If `getentropy` is available, then it's
-just a shim around that. Otherwise, it uses `getrandom(2)` (available
-since kernel 3.17) on Linux, or `/dev/urandom` on other \*nix.
+one symbol, `ent_getentropy`. If getentropy is available, then it's just
+a shim around that. Otherwise, it uses `getrandom(2)` (available since
+kernel 3.17) on Linux, or `/dev/urandom` on other \*nix.
 
 ### Building
 
 It uses meson. `meson ./build && ninja -C build` should do the trick.
 
-#### Build options
+The main intended way to use this library is to depend on it from
+another meson project, i.e., to pull `libent_dep` out from this library
+as a [subproject](https://mesonbuild.com/Subprojects.html). It's also
+possible to install it as a regular library if you want to for some
+reason — just run meson with `-Dent_install=true` and add on a `sudo
+ninja -C build install`.
 
-It has one option, `ent_compat`, which tells it to be conservative. On
-Linux, this means using `getrandom` directly; on other \*nix, it means
-reading from `/dev/urandom`. This may make sense if you want your
-binaries to run on older versions of the same OS. If your program is
-mostly built from source, don't bother.
+If you want to release a binary distribution of your program, you may
+want to build with `-Dent_compat=true`. This tells libent not to try to
+use getentropy, which might result in a program that can run against
+an older libc version on some platforms. (`ent_compat` does nothing on
+OpenBSD; we claim that 5.6 is old enough for anyone's purposes who wants
+to use this library.)
 
 ### Why?
 

include/meson.build

@@ -1 +1,3 @@
-#install_headers('ent.h')   # XX uncomment to install locally
+if get_option('ent_install')
+  install_headers('ent.h')
+endif

meson.build

@@ -1,9 +1,26 @@
-project('libent', 'c', version: '0.1.4', license: 'MIT')
+project('libent', 'c', version: '0.2.0', license: 'MIT')
 
 inc = include_directories('include')
 
 subdir('include')
 subdir('src')
 
-ent_sample = executable('sample', ['sample.c'],
-                        dependencies: [libent_dep])
+libent_dep = declare_dependency(
+  include_directories: inc,
+  link_with: libent,
+)
+
+ent_sample = executable(
+  'sample',
+  ['sample.c'],
+  dependencies: [libent_dep],
+)
+
+if get_option('ent_install')
+  pkg = import('pkgconfig')
+  pkg.generate(
+    libraries: [libent],
+    name: 'libent',
+    description: 'getentropy shim',
+  )
+endif

meson_options.txt

@@ -1,2 +1,4 @@
 option('ent_compat', type : 'boolean', value : false,
-       description : 'Tries to work on older systems. Useful for binary releases. (Uses getrandom on Linux, /dev/urandom on other *nix.)')
+       description : 'Don\'t rely on system getentropy')
+option('ent_install', type : 'boolean', value : false,
+       description : 'Install locally')

src/config.h.in

@@ -3,4 +3,3 @@
 #mesondefine ENT_GE_SYSRANDOM
 #mesondefine ENT_GETRANDOM
 #mesondefine ENT_URANDOM
-#mesondefine ENT_IMPL

src/ent.c

@@ -13,13 +13,13 @@
     return getentropy(buf, len);
   }
 
-#elif defined(ENT_IMPL)
+#elif defined(ENT_GETRANDOM) || defined(ENT_URANDOM)
 # include <errno.h>
 # if defined(ENT_GETRANDOM)
 #   define _GNU_SOURCE
 #   include <unistd.h>
 #   include <sys/syscall.h>
-# elif defined(ENT_URANDOM)
+# else
 #   include <stdio.h>
 # endif
 
@@ -41,7 +41,7 @@
     r = syscall(SYS_getrandom, buf, len, 0);
     if (r < 0)
       return r;
-# elif defined(ENT_URANDOM)
+# else
     {
       FILE *f;
 

src/meson.build

@@ -1,5 +1,5 @@
 conf_data = configuration_data()
-compiler = meson.get_compiler('c')
+cc = meson.get_compiler('c')
 # OpenBSD has had getentropy since 5.6. It's fine.
 compat = get_option('ent_compat') and host_machine.system() != 'openbsd'
 
@@ -9,14 +9,14 @@ if not compat
   #include <sys/random.h>
   int main() { return getentropy((void*)0, 0); }
   '''
-  sysrandom = compiler.links(code, name: 'getentropy in sys/random.h')
+  sysrandom = cc.links(code, name: 'getentropy in sys/random.h')
   conf_data.set('ENT_GE_SYSRANDOM', sysrandom)
 
   if not sysrandom
     code = '''#include <unistd.h>
     int main() { return getentropy((void*)0, 0); }
     '''
-    unistd = compiler.links(code, name: 'getentropy in unistd.h')
+    unistd = cc.links(code, name: 'getentropy in unistd.h')
   endif
   have_getentropy = sysrandom or unistd
   conf_data.set('ENT_GETENTROPY', have_getentropy)
@@ -31,21 +31,18 @@ if not have_getentropy
   #include <sys/syscall.h>
   int main() { return !syscall(SYS_getrandom, (void*)0, 0, 0); }
   '''
-  getrandom = compiler.links(code, name: 'getrandom syscall available')
+  getrandom = cc.links(code, name: 'getrandom syscall available')
   conf_data.set('ENT_GETRANDOM', getrandom)
 
   if not getrandom
     code = '''#include <stdio.h>
     int main() { return fopen("/dev/urandom", "r") ? 0 : 1; }
     '''
-    urandom = compiler.run(code, name: 'can open /dev/urandom').returncode() == 0
+    urandom = cc.run(code, name: 'can open /dev/urandom').returncode() == 0
     conf_data.set('ENT_URANDOM', urandom)
   endif
-  ent_impl = getrandom or urandom
-  conf_data.set('ENT_IMPL', ent_impl)
 endif
 
-
 config_file = configure_file(
   output: 'config.h',
   input: 'config.h.in',
@@ -54,9 +51,10 @@ config_file = configure_file(
 
 ent_sources = ['ent.c', config_file]
 
-libent = static_library('ent', ent_sources,
-                        include_directories: inc,
-                        c_args: ['-Wall', '-pedantic'],
-                        install: false)   # XX set to true to install locally
-
-libent_dep = declare_dependency(include_directories: inc, link_with: libent)
+libent = static_library(
+  'ent',
+  ent_sources,
+  include_directories: inc,
+  c_args: ['-Wall', '-pedantic'],
+  install: get_option('ent_install'),
+)