Fix the camera freeze on capture and run the API on Linux

.github/workflows/build.yml

@@ -107,7 +107,7 @@ jobs:
       run: dotnet test CanonSDK.sln --configuration Release --no-build
 
     - name: Publish Canon.API as standalone executable
-      run: dotnet publish Canon.API/Canon.API.csproj --configuration Release --runtime win-x64 --self-contained true -p:PublishSingleFile=true --output ./publish
+      run: dotnet publish Canon.API/Canon.API.csproj --configuration Release --framework net10.0-windows --runtime win-x64 --self-contained true -p:PublishSingleFile=true --output ./publish
 
     - name: Create release package
       run: |

CHANGELOG.md

@@ -7,6 +7,41 @@ Versions match the Git tags (`v1.0.0.11`) that trigger the release workflow.
 
 ## [Unreleased]
 
+### Added
+- `tools/Test-Camera.ps1` (with `Test-Camera.cmd`): runs the photo booth camera checks against the API (live view,
+  captures, flash changes during the live view, power cycle) and saves the pictures, the results and the API log.
+- Linux x64 support: the `net10.0` target of `Canon.API` runs on Linux with the Linux version of the EDSDK
+  (`EDSDK/linux-x64/libEDSDK.so`, needs `libusb-1.0`). No automatic update and no release package on Linux yet.
+- Debug logs (`Logging:LogLevel:Canon.Core` = `Debug`): every EDSDK event, and each step of a capture (UI lock, flash
+  settings, shutter button, transfer) with its result and duration.
+
+### Changed
+- `Canon.API` has two target frameworks: `dotnet run` and `dotnet publish` need `-f net10.0-windows` (Windows) or
+  `-f net10.0` (Linux). `Canon.Core` and the unit tests target `net10.0`.
+- A failed UI unlock after setting the flash is logged as a warning; it was ignored.
+- The problem title returned when the Canon EDSDK cannot be loaded now names both platforms: "Canon EDSDK could not be
+  loaded (EDSDK.dll or libEDSDK.so missing, wrong architecture, or libusb-1.0 missing on Linux)" (was "...(EDSDK.dll
+  missing or wrong architecture)"). Client-visible text.
+- Regenerating `docs/openapi.json` at build time now uses
+  `dotnet build Canon.API -f net10.0 -t:Build -t:GenerateOpenApiDocuments` (Windows or Linux); the former
+  `-p:OpenApiGenerateDocumentsOnBuild=true` form generates nothing now that `Canon.API` has two target frameworks.
+
+### Fixed
+- The camera froze when a picture was taken while the live view ran, as in the photo booth: the shutter stayed busy
+  (503 "Camera busy"), no picture was returned, and the camera did not respond until it was turned off and on. Writing
+  the flash setting during the live view freezes the camera (EOS R100), and `Canon:ForceFlashFiring` wrote it before
+  every capture. It is now written when the camera connects, before the live view starts (once per live view session)
+  and before a capture taken without live view; `POST /flash` pauses the live view while it writes it. With
+  `Canon:ForceFlashFiring`, a value set with `POST /flash` therefore stays until the live view stops (it was set back to
+  Fire before every capture), and `GET /flash` returns the last value set while the live view runs.
+- Linux: the application crashed when the camera was turned off or unplugged. The SDK closes the session itself then,
+  and releasing the camera closed it a second time, which crashed (`CLinuxPtpHelper::Terminate` from `EdsRelease`). On
+  Linux the camera object of a camera that is gone is now left to the SDK.
+- The session of a camera that is gone (turned off, unplugged, or a call failed because it is disconnected) is no longer
+  closed before the camera is released, on Windows too, as in the Canon samples.
+- Linux: a camera turned back on or plugged back in was not reconnected, because the SDK lists it a moment after
+  reporting it (about 1 s). The connection is now retried for about 10 s.
+
 ## [1.4.0.0] - 2026-09-30
 
 ### Added

CLAUDE.md

@@ -10,10 +10,10 @@ CanonWebAPI is a .NET 10 web API for remotely controlling Canon DSLR and mirrorl
 
 The solution consists of 4 projects:
 
-- **Canon.API**: ASP.NET Core Web API (main entry point)
+- **Canon.API**: ASP.NET Core Web API (main entry point); targets `net10.0-windows` (Windows release, AutoUpdater.NET) and `net10.0` (Linux, no automatic update)
 - **Canon.Core**: Core library wrapping Canon EDSDK functionality
 - **Canon.Core.Tests**: xUnit unit tests of Canon.Core (no camera needed, run on Linux too)
-- **Canon.API.Tests**: xUnit unit tests of the pure parts of Canon.API, compiled from linked sources (Canon.API needs the Windows Desktop runtime)
+- **Canon.API.Tests**: xUnit unit tests of the pure parts of Canon.API, compiled from the Canon.API sources so they do not depend on the API project and its packages
 
 ### Key Components
 
@@ -30,9 +30,10 @@ The solution consists of 4 projects:
 ### Dependencies
 
 - Requires Canon EDSDK 13.20.21 **64-bit** DLLs (`EDSDK.dll`, `EdsImage.dll`, from `EDSDK_64/Dll` of the SDK) in the EDSDK folder
+- Linux: `EDSDK/linux-x64/libEDSDK.so` (from `EDSDK/Library/x86_64` of the 13.20.21 Linux SDK), needs `libusb-1.0`
 - Uses Serilog for logging
 - Swagger/OpenAPI for API documentation
-- Platform target: x64 (Windows only)
+- Platform target: x64 (Windows; Linux through the `net10.0` target of Canon.API)
 
 ## Development Commands
 
@@ -43,7 +44,7 @@ dotnet build CanonSDK.sln
 
 ### Run API Server
 ```bash
-dotnet run --project Canon.API
+dotnet run --project Canon.API -f net10.0-windows   # Linux: -f net10.0 --launch-profile http
 ```
 
 ### Run Unit Tests
@@ -79,7 +80,7 @@ The Canon.API project exposes these REST endpoints (OpenAPI at `/openapi/v1.json
 - GET `/latestpicture` - Retrieve last captured image
 - POST `/autofocus` - Trigger autofocus
 - GET `/cameraname`, `/mode`, `/temperature`, `/status` - Camera information
-- GET/POST `/flash` - "Flash firing" setting (forced to Fire before each capture by default)
+- GET/POST `/flash` - "Flash firing" setting (forced to Fire by default, outside the live view)
 
 Errors are problem details: 400 invalid value, 409 capture refused or setting locked by the shooting mode, 503 not connected/busy, 504 capture timeout.
 
@@ -88,7 +89,7 @@ Errors are problem details: 400 invalid value, 409 capture refused or setting lo
 - The camera can be connected via USB before or after the application starts (automatic connection and reconnection)
 - Canon EOS Utility must NOT be running (conflicts with EDSDK access)
 - Requires compatible Canon camera with EDSDK support
-- All projects target .NET 10 (`net10.0-windows`) with Windows-specific dependencies
+- Canon.Core and the tests target `net10.0`; Canon.API targets `net10.0-windows` (release, AutoUpdater.NET) and `net10.0` (Linux). Publish the release with `-f net10.0-windows`
 - Uses structured logging with Serilog (logs to console and `logs/canon-api.log` next to the executable; levels from `Logging:LogLevel`)
 - Content root is the executable folder: settings files are read next to the executable whatever the working directory
 - Operator settings go in `appsettings.Local.json`, never shipped: automatic updates overwrite `appsettings.json`
@@ -97,6 +98,8 @@ Errors are problem details: 400 invalid value, 409 capture refused or setting lo
 
 ## AutoUpdater Integration
 
+Applies to the `net10.0-windows` target only: the `net10.0` target (Linux) has no automatic update.
+
 The application includes AutoUpdater.NET with these configurations:
 - Automatic version checking on startup
 - No admin privileges required (`RunUpdateAsAdmin = false`)
@@ -122,9 +125,9 @@ The project uses GitHub Actions for automated releases (record every change in t
 - Downloads go to memory streams; the progress callback is registered before `EdsDownload`
 - Live view is started with `Evf_OutputDevice` and stopped when no client uses it
 - "Device busy" answers are retried after ~500 ms, as in the Canon samples; only the shutter press is retried, the release is always sent
-- Flash (`EdsCreateFlashSettingRef`, `Flash_Target`, `Flash_Firing`): the UI must be locked while setting it; the SDK only reports values set remotely, so the setting is forced before each capture (studio flash on the shoe in the photo booth)
+- Flash (`EdsCreateFlashSettingRef`, `Flash_Target`, `Flash_Firing`): the UI must be locked while setting it; the SDK only reports values set remotely, so the setting is forced when the camera connects, before the live view starts and before a capture without live view (studio flash on the shoe in the photo booth). Never write it while the live view runs: the EOS R100 freezes (shutter busy until it is turned off and on); POST /flash pauses the live view
 - Settings: `CameraSettingRules` (pure, tested) decides what is settable per AE mode; EdsGetPropertyDesc gives the accepted values (its `form`/`access` fields are reserved, always 0); an empty list means not settable now (as in the Canon samples). Set only values from that list (API reference 3.1.20)
-- Memory management critical due to unmanaged EDSDK resources: release every ref (`EdsRelease`)
+- Memory management critical due to unmanaged EDSDK resources: release every ref (`EdsRelease`), except, on Linux, a camera that is gone: the SDK has already closed its session and releasing it crashes (`CLinuxPtpHelper::Terminate`)
 
 ## Testing
 

Canon.API.Tests/CameraExceptionHandlerTests.cs

@@ -28,6 +28,8 @@ public class CameraExceptionHandlerTests
         { NotApplied(new EdsException(EDSDK.EDS_ERR_DEVICE_BUSY, "x")), 503 },
         { NotApplied(new EdsException(EDSDK.EDS_ERR_INVALID_DEVICEPROP_VALUE, "x")), 400 },
         { new InvalidOperationException(), 500 },
+        { new DllNotFoundException("x"), 500 },
+        { new BadImageFormatException("x"), 500 },
     };
 
     private static CameraSettingsException Refused(SettingErrorReason reason) =>

Canon.API.Tests/Canon.API.Tests.csproj

@@ -1,18 +1,15 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net10.0-windows</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <PlatformTarget>x64</PlatformTarget>
     <IsPackable>false</IsPackable>
     <IsTestProject>true</IsTestProject>
   </PropertyGroup>
 
-  <!--
-    Canon.API needs the Windows Desktop runtime (AutoUpdater.NET): referencing it would make these tests Windows only.
-    The parts under test do not depend on it, so their sources are compiled here instead.
-  -->
+  <!-- The parts under test are compiled from the Canon.API sources, so these tests do not depend on the API project and its packages. -->
   <ItemGroup>
     <Compile Include="..\Canon.API\Infrastructure\CameraExceptionHandler.cs" Link="Linked\CameraExceptionHandler.cs" />
     <Compile Include="..\Canon.API\Infrastructure\LogLevels.cs" Link="Linked\LogLevels.cs" />

Canon.API/Canon.API.csproj

@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
-    <TargetFramework>net10.0-windows</TargetFramework>
+    <!-- net10.0-windows: Windows release, with AutoUpdater.NET (Windows Desktop runtime). net10.0: Linux, no automatic update. -->
+    <TargetFrameworks>net10.0-windows;net10.0</TargetFrameworks>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
 	  <PlatformTarget>x64</PlatformTarget>
@@ -11,17 +12,20 @@
     <FileVersion>1.4.0.0</FileVersion>
     <Version>1.4.0.0</Version>
 
-    <!-- Self-Contained Single-File Deployment -->
+    <!-- OpenAPI document generated at build time only when requested (see README). Keep false: the package's outer-build hook
+         would otherwise generate from net10.0-windows before every solution build. -->
+    <OpenApiGenerateDocumentsOnBuild>false</OpenApiGenerateDocumentsOnBuild>
+    <OpenApiDocumentsDirectory>$(MSBuildProjectDirectory)/../docs</OpenApiDocumentsDirectory>
+    <OpenApiGenerateDocumentsOptions>--file-name openapi</OpenApiGenerateDocumentsOptions>
+  </PropertyGroup>
+
+  <!-- Self-Contained Single-File Deployment (Windows release) -->
+  <PropertyGroup Condition="'$(TargetFramework)' == 'net10.0-windows'">
     <PublishSingleFile>true</PublishSingleFile>
     <SelfContained>true</SelfContained>
     <RuntimeIdentifier>win-x64</RuntimeIdentifier>
     <IncludeNativeLibrariesForSelfExtract>true</IncludeNativeLibrariesForSelfExtract>
     <EnableCompressionInSingleFile>true</EnableCompressionInSingleFile>
-
-    <!-- OpenAPI document generated at build time only when requested (see README) -->
-    <OpenApiGenerateDocumentsOnBuild>false</OpenApiGenerateDocumentsOnBuild>
-    <OpenApiDocumentsDirectory>$(MSBuildProjectDirectory)/../docs</OpenApiDocumentsDirectory>
-    <OpenApiGenerateDocumentsOptions>--file-name openapi</OpenApiGenerateDocumentsOptions>
   </PropertyGroup>
 
   <ItemGroup>
@@ -37,17 +41,45 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Autoupdater.NET.Official" Version="1.9.3" />
     <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="10.0.12" />
     <PackageReference Include="Serilog.AspNetCore" Version="10.0.0" />
     <PackageReference Include="Swashbuckle.AspNetCore.SwaggerUI" Version="10.2.3" />
-    <!-- Build-time generation of docs/openapi.json, opt-in: dotnet build -p:OpenApiGenerateDocumentsOnBuild=true -->
+    <!-- Build-time generation of docs/openapi.json, opt-in: dotnet build -f net10.0 -t:Build -t:GenerateOpenApiDocuments
+         (the package hook skips the inner builds of a multi-targeted project, so -p:OpenApiGenerateDocumentsOnBuild=true
+         with -f generates nothing; net10.0 keeps the Windows update check out of the generator, which runs the application's
+         entry point) -->
     <PackageReference Include="Microsoft.Extensions.ApiDescription.Server" Version="10.0.12">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetFramework)' == 'net10.0-windows'">
+    <PackageReference Include="Autoupdater.NET.Official" Version="1.9.3" />
+  </ItemGroup>
+
+  <!-- Canon EDSDK native libraries, next to the executable (outside the single file). -->
+  <ItemGroup Condition="'$(TargetFramework)' == 'net10.0-windows'">
+    <None Include="..\EDSDK\EDSDK.dll" Link="EDSDK.dll">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      <CopyToPublishDirectory>PreserveNewest</CopyToPublishDirectory>
+      <ExcludeFromSingleFile>true</ExcludeFromSingleFile>
+    </None>
+    <None Include="..\EDSDK\EdsImage.dll" Link="EdsImage.dll">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      <CopyToPublishDirectory>PreserveNewest</CopyToPublishDirectory>
+      <ExcludeFromSingleFile>true</ExcludeFromSingleFile>
+    </None>
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(TargetFramework)' == 'net10.0'">
+    <None Include="..\EDSDK\linux-x64\libEDSDK.so" Link="libEDSDK.so">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      <CopyToPublishDirectory>PreserveNewest</CopyToPublishDirectory>
+      <ExcludeFromSingleFile>true</ExcludeFromSingleFile>
+    </None>
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\Canon.Core\Canon.Core.csproj" />
   </ItemGroup>

Canon.API/Controllers/CanonController.cs

@@ -69,13 +69,13 @@ public async Task<IActionResult> GetStatus()
 
     [HttpGet("flash")]
     [EndpointSummary("State of the \"flash firing\" setting")]
-    [EndpointDescription("The SDK only reports values set remotely: 'firing' is the value last set by the API (null before the first one). A change made in the camera menu is not visible. With Canon:ForceFlashFiring (default), the setting is set to Fire when the camera connects and before every capture.")]
+    [EndpointDescription("The SDK only reports values set remotely: 'firing' is the value last set by the API (null before the first one). A change made in the camera menu is not visible. With Canon:ForceFlashFiring (default), the setting is set to Fire when the camera connects, before the live view starts and before a capture taken without live view (never while the live view runs, which would freeze the camera).")]
     [ProducesResponseType<FlashStatus>(StatusCodes.Status200OK, "application/json")]
     public async Task<IActionResult> GetFlash() => Ok(await camera.GetFlashStatus());
 
     [HttpPost("flash")]
     [EndpointSummary("Set the \"flash firing\" setting (\"fire\" or \"off\")")]
-    [EndpointDescription("The camera must be in P, Tv, Av or M. With Canon:ForceFlashFiring (default), the setting is set back to Fire before the next capture.")]
+    [EndpointDescription("The camera must be in P, Tv, Av or M. A running live view is paused while the setting is written, because writing it during the live view freezes the camera. With Canon:ForceFlashFiring (default), the setting is set back to Fire the next time the live view starts or before the next capture taken without live view.")]
     [ProducesResponseType<FlashStatus>(StatusCodes.Status200OK, "application/json")]
     [ProducesResponseType<ProblemDetails>(StatusCodes.Status400BadRequest, "application/problem+json")]
     [ProducesResponseType<ProblemDetails>(StatusCodes.Status409Conflict, "application/problem+json")]

Canon.API/Infrastructure/CameraExceptionHandler.cs

@@ -115,7 +115,7 @@ private static void AddSettingsExtensions(ProblemDetails problem, CameraSettings
         EdsException { IsRefused: true } => (StatusCodes.Status409Conflict, "Operation refused by the camera"),
         EdsException { IsInvalidValue: true } => (StatusCodes.Status400BadRequest, "Value not accepted by the camera"),
         EdsException => (StatusCodes.Status500InternalServerError, "Camera error"),
-        DllNotFoundException or BadImageFormatException => (StatusCodes.Status500InternalServerError, "Canon EDSDK could not be loaded (EDSDK.dll missing or wrong architecture)"),
+        DllNotFoundException or BadImageFormatException => (StatusCodes.Status500InternalServerError, "Canon EDSDK could not be loaded (EDSDK.dll or libEDSDK.so missing, wrong architecture, or libusb-1.0 missing on Linux)"),
         _ => (StatusCodes.Status500InternalServerError, "Internal server error")
     };
 }

Canon.API/Program.cs

@@ -1,6 +1,8 @@
 using Canon.API.Infrastructure;
 using Serilog;
+#if WINDOWS
 using AutoUpdaterDotNET;
+#endif
 
 // Next to the executable, whatever the working directory (shortcut, scheduled task...).
 var logFile = Path.Combine(AppContext.BaseDirectory, "logs", "canon-api.log");
@@ -48,10 +50,14 @@
 
     var app = builder.Build();
 
+#if WINDOWS
     if (app.Configuration.GetValue("AutoUpdate:Enabled", true))
         ConfigureAutoUpdater(app);
     else
         Log.Information("Automatic updates are disabled");
+#else
+    Log.Information("Automatic updates are not available on this platform");
+#endif
 
     app.UseExceptionHandler();
 
@@ -75,6 +81,7 @@
     Log.CloseAndFlush();
 }
 
+#if WINDOWS
 static void ConfigureAutoUpdater(WebApplication app)
 {
     // Configure AutoUpdater.NET for automatic updates
@@ -99,3 +106,4 @@ static void ConfigureAutoUpdater(WebApplication app)
 
     AutoUpdater.Start(app.Configuration["AutoUpdate:Url"] ?? "https://dansleboby.github.io/CanonWebAPI/autoupdate.xml");
 }
+#endif

Canon.Core.Tests/Canon.Core.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net10.0-windows</TargetFramework>
+    <TargetFramework>net10.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
     <PlatformTarget>x64</PlatformTarget>

Canon.Core.Tests/EdsdkHelperTests.cs

@@ -137,4 +137,23 @@ public void Capture_errors_are_translated(uint code, string message)
     {
         Assert.Equal(message, EdsdkHelper.GetCaptureErrorMessage(code));
     }
+
+    [Theory]
+    [InlineData(EDSDK.StateEvent_Shutdown, "StateEvent_Shutdown")]
+    [InlineData(EDSDK.StateEvent_CaptureError, "StateEvent_CaptureError")]
+    [InlineData(EDSDK.ObjectEvent_DirItemRequestTransfer, "ObjectEvent_DirItemRequestTransfer")]
+    [InlineData(EDSDK.PropertyEvent_PropertyChanged, "PropertyEvent_PropertyChanged")]
+    [InlineData(0xABCDu, "0xABCD")]
+    public void Events_are_named_after_their_constant(uint eventId, string name)
+    {
+        Assert.Equal(name, EdsdkHelper.DescribeEvent(eventId));
+    }
+
+    [Fact]
+    public void Results_are_described_with_their_code()
+    {
+        Assert.Equal("OK", EdsdkHelper.DescribeResult(EDSDK.EDS_ERR_OK));
+        Assert.Equal("Device is busy (0x2019)", EdsdkHelper.DescribeResult(EDSDK.EDS_ERR_PTP_DEVICE_BUSY));
+        Assert.Equal("0x12345678", EdsdkHelper.DescribeResult(0x12345678));
+    }
 }